PHY 112 Final Prep

The team monitoring a space probe exploring the outer solar system finds that radio trasmissions from the probe take 1.36 hours to reach earth. How distant (in meters) is the probe?

1.47e12 m

True or False: The speed of light in a vacuum depends only on the electric permittivity of free space. a. False b. True

a

A single-loop circuit consists of a 9.0 V battery and a 22 Ω resistor. How much current will flow in this circuit? 0.41 A 31 A 2.4 A 198 A

A

What is the greatest distance an image can be located behind a convex spherical mirror? di=-F di=-F/2 di= infinity

A

Calculate the magnification of the image when an object is placed at a distance do=2f to the left of a converging lens. Is the image inverted or upright? m= 1, upright. m= -1, inverted. m= -1, upright. m= 2, upright. m= -2, inverted.

B

A changing magnetic field induces an emf of 5.0 V in a single-loop of wire. Suppose the single loop were replaced by one continuous wire wrapped to form a coil of five loops, each with the same size and shape as the original loop, and placed in the same changing magnetic field and with the same orientation as the single loop. What would be the magnitude of the induced emf in the coil? a. 25 V b. 1.0 V c. 0 V d. 5.0 V

a

A circular loop of wire is positioned so the normal to its area points vertically upward. A bar magnet is dropped from above the loop so that its north pole falls through the loop first. When looking at the loop from above, in which direction is the induced current in the loop just as the north pole of the magnet enters the loop? a. Counterclockwise b. There is no induced current c. Clockwise

a

Suppose a circular coil is placed in a uniform magnetic field B. Which of the following creates the emf of the largest magnitude? a. Keeping the direction of the field parallel to the normal to the area of the coil and decreasing the field uniformly from B to zero in 2.0 s. b. Doubling the field value from B to 2B in 2.0 s. c. Keeping the field at value B and rotating the coil so that the normal to the coil's loop area rotates 360o relative to the field direction (i.e., one complete revolution) in 2.0 s.

c

For the example of refraction illustrated in the drawing θ1 = 60° and θ2 = 71.0°. Calculate the ratio n1/n2 of the indices of refraction of the two materials.

m1/m2= 1.09 no units

A mixture of red and violet light is incident on a glass-air interface, as the drawing shows. The indices of refraction for red and violet light in glass are nred = 1.520 and nviolet = 1.538. What color(s) of light enters the air? Only red Both violet and red Neither violet nor red Only violet

A

The battery charger for an MP3 player contains a step-down transformer with a turns ratio of 1:22, so that the voltage of 120 V available at a wall socket can be used to charge the battery pack or operate the player. What voltage does the secondary coil of the transformer provide?

5.45 V

A tiny ball (mass = 0.015 kg) carries a charge of -25C. What is the electric field magnitude that would cause the ball to float above the ground?

5.88e3 N/C

An electric blanket is connected to a 120-V outlet and consumes 280 W of power. What is the resistance of the heater wire in the blanket?

51.4 ohms

Consider the circuit in the drawing. Determine (a) the magnitude of the current in the circuit and (b) the magnitude of the voltage between the points labeled A and B.

A. 0.3846 A B. 19.62 V

A friend is standing 2 m in front of a plane mirror. You are standing 3 m directly behind your friend. What is the distance between you and the image of your friend? 5 m 3 m 10 m 7 m 2 m

D

A ray is __________ always parallel to other rays. parallel to the wave fronts. perpendicular to the velocity of the wave. parallel to the velocity of the wave.

D

A wave front __________ is a surface that contains one cycle of the wave. is always a plane surface. is parallel to a ray. is a surface on which all points of the wave are in the same phase of motion. is always a spherical surface.

D

Suppose that the electric potential outside a living cell is higher than that inside the cell by 0.093 V. How much work is done by the electric force when a sodium ion (charge = +e) moves from the outside to the inside?

1.49e-20 J

The electric potential energy stored in the capacitor of a defibrillator is 100 J, and the capacitance is 170 μF. What is the potential difference across the capacitor plates?

1084.7 V

Iron atoms have been detected in the sun's atmosphere, some with many of their electrons stripped away. What is the net electric charge (in coulombs) of an iron atom with 26 protons and 6 electrons? Be sure to include the algebraic sign (+ or -) in your answer.

3.2e-18 C

A 58-W lamp is placed in series with a resistor and a 120-V source. If the voltage across the lamp is 35 V, what is the resistance R of the resistor?

51.3 ohms

The inner and outer surfaces of a cell membrane carry a negative and positive charge, respectively. Because of these charges, a potential difference of about 0.077 V exists across the membrane. The thickness of the membrane is 8.0 x 10-9 m. What is the magnitude of the electric field in the membrane?

9.63e6 N/C

A diffraction pattern is created on a screen when blue light is passed through a single slit. Does the central bright maximum in this pattern become wider or narrower, when the blue light is replaced by red light? Wider Narrower The width remains the same.

A

A positive charge is moving with velocity v through a region of space where a uniform magnetic field exists everywhere into the screen, as the figure shows. What is the direction of the magnetic force on the charge just as it enters the field? Upward Right Left Downward

A

A sound wave has a much greater wavelength than a light wave. If both waves pass through an open doorway, which one, if either, will diffract to a greater extent. The sound wave The light wave Both would diffract by the same amount.

A

A square current-carrying loop is placed in a uniform magnetic field B, with the plane of the loop perpendicular to the direction of the field. The dashed line is the axis of rotation. The magnetic field exerts _____ neither a net force nor a net torque on the loop. a net force and a net torque on the loop. a net force, but not a net torque, on the loop. a net torque, but not a net force, on the loop.

A

A thin film with a refractive index of 1.20 is surrounded by air on both sides. What is the minimum nonzero thickness for this film when it appears red in light with a wavelength in vacuum of 650 nm? 135 nm 68 nm 270 nm 203 nm

A

An object is situated at a known distance in front of a convex mirror whose focal length is also known. A friend of yours does a calculation that shows that the magnification is -2. After some thought, you conclude correctly that __________ the magnification should be + 1/2. the magnification should be - 1/2. your friend's answer is correct. the magnification should be +2

A

Consider a converging lens with a focal point F. Without changing the shape and size of the lens, what could you do to move the focus closer to the lens? Make the lens from a material with a larger index of refraction. Make the lens from a material with a smaller index of refraction. There is nothing you can do: the shape alone determines the focal length

A

Is it possible for a converging lens to focus the image of an object on a screen if the object located between the focal point and the lens? No, because the image is virtual and forms on the same side of the lens as the object. No, because there is no focused image of any kind formed in this case. Yes.

A

Light rays that are near and parallel to the principal axis of a concave mirror converge to a point 18 cm in front of the mirror. What is the radius of curvature of the mirror? 36 cm 18 cm 9 cm -9 cm -18 cm

A

Light reflecting off of a rough piece of paper is an example of? Diffuse reflection Specular reflection Reverse reflection Secondary reflection

A

Suppose a converging lens focuses parallel light at a point F to its right. If you place a second, identical lens so that its focal point (on its left) is located at point F, what happens on the right of the second lens? The light is parallel to the principal axis on the right of the second lens. The light is focused at the focal point to the right of the second lens. The light diverges on the right of the second lens.

A

Suppose the light waves coming from both slits in a Young's double-slit experiment had their phases shifted by an amount equivalent to a half-wavelength. Would the pattern on the screen be the same, or would the bright and dark fringes be interchanged? The pattern on the screen would be the same. The bright and dark fringes would be interchanged.

A

The drawing shows a rectangular block of glass (n = 1.52) surrounded by air. A ray of light starts out within the glass and travels toward point A, where some or all of it is reflected toward point B. At which points does some of the light escape the glass? Only at point A Only at point B At both points A and B At neither point A nor point B

A

The drawing shows a top view of an object located to the right of a mirror. A single ray of light is shown leaving the object. After reflection from the mirror, through which location, A, B, C, or D, does the ray pass? C B D A

A

The figure shows a light ray undergoing multiple reflections from a mirrored corridor. The walls of the corridor are either parallel or perpendicular to one another. If the initial angle of incidence is 35o, what is the angle of reflection (θ) when the ray makes its last reflection? 55o 65o 35o 45o

A

The figure shows three particles with identical charge magnitudes and masses moving through a uniform magnetic field inside a bubble chamber. Which particle has the greatest speed? 1: spin up 2: spin down 3: spin out 3 1 2

A

The indices of refraction for red, green, and violet light in glass are nred = 1.520, ngreen = 1.526, and nviolet = 1.538. When a ray of light passes through a transparent slab of glass, the emergent ray is parallel to the incident ray, but can be displaced relative to it unless the angle of incidence is zero. For light passing through a glass slab that is surrounded by air, which color is displaced the most? Violet All colors are displaced equally. Red Green

A

Three point charges have equal magnitudes and are fixed to the corners of an equilateral triangle. Two of the charges are positive and one is negative, as the drawing shows. At which one of the corners is the net force acting on the charge directed parallel to the x axis? B A C

A

True or False: X-ray diffraction from crystalline matter can provide information on the spacing of atoms and the nature of the crystal structure. True False

A

Two sources of waves are in phase and produce identical waves. These sources are mounted at the corners of a square and broadcast waves uniformly in all directions. At the center of the square, will the waves always produce constructive interference no matter which two corners of the square are occupied by the sources? Yes No

A

What is the function of the third prong on a power cord to a device? It provides a safe path to ground in case there is a broken wire inside the device. It is an extra input line for devices that need a lot of power. It serves no purpose.

A

When diffuse reflection from a surface occurs, __________ the reflected rays are not parallel to each other. there are no reflected rays. an individual ray of light does not obey the law of reflection. the reflected rays are parallel to each other.

A

Which of the following does not produce a change in magnetic flux through a square loop of wire? a. The loop falls through a uniform magnetic field without rotating. b. The loop falls through a region of constant magnetic field into a region of zero magnetic field. c. The loop falls through a region of zero magnetic field into a region of constant magnetic field. d. The loop rotates haphazardly while it falls through a uniform magnetic field.

A

Which of the following is not a property of an image formed by a plane mirror? The image is real. The image is located as far behind the mirror as the object is in front. The image is reversed from left to right. The image is upright with respect to the object. The image is virtual.

A

X-rays diffract from crystalline matter because... The wavelength of the X-rays is comparable to the atomic spacing in matter. The wavelength of the X-rays is much larger than the atomic spacing in matter. The wavelength of the X-rays is much shorter than the atomic spacing in matter.

A

A defibrillator is used during a heart attack to restore the heart to its normal beating pattern. A defibrillator passes 16 A of current through the torso of a person in 2.0 ms. (a) How much charge moves during this time? (b) How many electrons pass through the wires connected to the patient?

A. 0.032 C B. 2.0e17 no units

The membrane that surrounds a certain type of living cell has a surface area of 5.2 x 10-9 m2 and a thickness of 1.4 x 10-8 m. Assume that the membrane behaves like a parallel plate capacitor and has a dielectric constant of 4.4. (a) The potential on the outer surface of the membrane is +70.9 mV greater than that on the inside surface. How much charge resides on the outer surface? (b) If the charge in part (a) is due to K+ ions (charge +e), how many such ions are present on the outer surface?

A. 1.03e-12 C B. 6.41e6 no units

Suppose that the resistance between the walls of a biological cell is 6.5 × 109 Ω. (a) What is the current when the potential difference between the walls is 69 mV? (b) If the current is composed of Na+ ions (q = +e), how many such ions flow in 0.68 s?

A. 1.06e-11 A B. 4.51e7 no units

Three resistors, 28 Ω, 64 Ω, and 83 Ω, are connected in series, and a 0.72-A current passes through them. What are (a) the equivalent resistance and (b) the potential difference across this equivalent resistance?

A. 175 ohms B. 126 V

Refer to Interactive Solution 19.45 for one approach to this problem. The electronic flash attachment for a camera contains a capacitor for storing the energy used to produce the flash. In one such unit, the potential difference between the plates of an 830-μF capacitor is 300 V. (a) Determine the energy that is used to produce the flash in this unit. (b) Assuming that the flash lasts for 6.4 ms, find the effective power or "wattage" of the flash.

A. 37.4 J B. 5843.75 W

Refer to Interactive Solution 19.37 to review a method by which this problem can be solved. The electric field has a constant value of 4.2 x 104 V/m and is directed downward. The field is the same everywhere. The potential at a point P within this region is 201 V. Find the potential at the following points: (a) 8.9 x 10-3 m directly above P, (b) 3.8 x 10-3 m directly below P, (c) 7.1 x 10-3 m directly to the right of P.

A. 574.8 V B. 41.4 V C. 201 V

the drawing shows a circuit that contains a battery, two resistors, and a switch. What is the equivalent resistance of the circuit when the switch is (a) open and (b) closed? What is the total power delivered to the resistors when the switch is (c) open and (d) closed?

A. 65 ohms B. 38.75 ohms C. 1.25 W D. 2.09 W

A current carrying wire is experiencing a magnetic force in a magnetic field. What happens to the direction of the magnetic force on the wire, if the current in the wire is reversed? Nothing. The magnitude and direction of the force remain unchanged. The magnitude of the force remains unchanged, but it reverses direction. The magnitude of the force remains unchanged, but it is oriented perpendicular to the direction of the original force. The magnitude of the forces decreases, but it remains in the same direction.

B

A proton is released from rest at a location in space where the magnetic field points upward toward the top of the page. Which of the following is true? The proton experiences a magnetic force to the right. The proton experiences no magnetic force and remains at rest. The proton experiences a magnetic force upward. The proton experiences a magnetic force downward.

B

A square current-carrying loop is placed in a uniform magnetic field B with the plane of the loop parallel to the magnetic field (see the drawing). The dashed line is the axis of rotation. The magnetic field exerts __________ a net force, but not a net torque, on the loop. a net torque, but not a net force, on the loop. neither a net force nor a net torque on the loop. a net force and a net torque on the loop.

B

An electrically isolated object is electrically neutral. What is the charge on the object if you remove three electrons? Zero +3e -3e Impossible to tell

B

An incident beam of light moves through liquid water (n= 1.33) and impinges upon an interface with glass (n= 1.52) with an angle of incidence of 47.0o.What is the angle of the refracted beam (i.e., in the glass) with respect to the surface normal? 47.0o 39.8o 28.6o 56.7o

B

An object is placed at a known distance in front of a mirror whose focal length is also known. You apply the mirror equation and find that the image distance is a negative number. This result tells you that __________ the image is larger than the object. the image is virtual. the image is real. the image is smaller than the object. the image is inverted relative to the object.

B

Based on how the size of your pupils responds to light levels, when would human eyes have their best optical resolution? In bright sunshine. At night Light levels would not affect optical resolution.

B

Because of spherical aberration, a parallel ray far from the principal axis does not pass through the focal point upon reflection (see figure). How could you change the shape of the mirror, so the ray does pass through F after reflection? Close the mirror down by bringing the ends of the mirror closer to the principal axis. Open it up by moving the ends of the mirror away from the principal axis, thereby creating a more gentle curvature.

B

Four views of a horseshoe magnet and a current-carrying wire are shown in the drawing. The wire is perpendicular to the screen, and the current is directed out of the screen toward you. In which one or more of these situations does the magnetic force on the current point due north? 1: up, current out of screen 2: up 3: right 4: left 3 1 1 and 2 3 and 4 2

B

If a glass prism (n= 1.52) were surrounded by water (n= 1.33) rather than air (n= 1.00) how would the dispersion of the light change? The colors would be more spread out (i.e., more dispersed). The colors would be less spread out (i.e., less dispersed). There would be no change.

B

In light sources that utilize electrical gas discharge, like in neon signs, the emitted light is composed of discrete colors rather than the full spectrum (such as in sunlight). Even though the gas discharge source emits multiple colors of light, your eyes can only detect one color. If the light from a gas discharge source is passed through a prism, what will you see? Only one color: the one that your eyes detect emitted from the source. A series of individual colors located where they would otherwise be in the full spectrum (but the other colors in the spectrum are missing). A continuous spectrum, the same as for sunlight.

B

Red and blue light are simultaneously passed through a diffraction grating. The first-order maxima for the red light is located 20 cm from middle of the central bright fringe. Where is the first-order maxima for the blue light located? Also at 20 cm from the middle of the central bright fringe Less than 20 cm from the middle of the central bright fringe Greater than 20 cm from the middle of the central bright fringe

B

Suppose an unknown circuit draws 8.0 A of current when 110 V is applied across its inputs. What is the power dissipated by this circuit? 0.07 W 880 W Impossible to know. 13.8 W

B

Suppose that a current of 1.5 A is used to charge a conductor. After 4.0 s, how much charge is delivered to the conductor. 2.7 V 6.0 C 2.7 C 6.0 V

B

The direction of propagation of which color of light (ROYGBIV) changes the most as the light passes through a prism? red violet green They all change by the same angle.

B

The drawing shows a top view of an object to the right of a plane mirror. An observer looks into the mirror. At what location, A, B, C, or D, does the observer see the image? C A D The observer does not see an image because the observer is closer to the mirror than is the object. B

B

The nucleus of the nitrogen atom has 7 protons. How many electrons does an electrical neutral nitrogen atom have? Impossible to tell 7 0 3

B

The same current-carrying wire is placed in the same magnetic field, but in different orientations. Rank the magnetic force on each wire, starting with the largest. A: 45 degree angle B: right C: straight up A, B, C B, A, C C, B, A C, A, B

B

Three long, straight wires are carrying currents that have the same magnitude. In C the current is opposite to that in A and B. The wires are equally spaced. Each wire experiences a net force due to the other two wires. Which wire experiences a net force that has the greatest magnitude? A: right B: right C: left A B C All three wires experience a net force that has the same magnitude.

B

True or False: Compact discs (CDs) and digital video discs (DVDs) rely on interference effects of light for their operation. False True

B

True or False: It is possible to use a convex spherical mirror to produce an enlarged image. True False

B

Two identical resistors (R) are wired in series with a battery of voltage V. Suppose one of the resistors is removed from the circuit. How does the power dissipation of the single resistor compare to the power dissipation of that resistor when the second resistor was in the circuit? The power dissipation is halved. The power dissipation is quadrupled. It is the same. The power dissipation is doubled.

B

When the demonstrator moves the light upward, the image will becomes sharper. move downward. move upward. not move.

B

Where is the image located in the case of an object placed at a distance do=2f to the left of a converging lens? f 2f -2f f/2

B

Which of the following is true at a very far distance from a wave source? The wave fronts reaching you are curved, and the rays are not parallel to each other. The wave fronts reaching you form flat planes, and the rays are parallel to each other. The wave fronts reaching you are curved, and the rays are parallel to each other. The wave fronts reaching you form flat planes, and the rays are not parallel to each other.

B

Which of the following is/are true? I. The earth has a magnetic field. II. The earth's magnetic field is similar to a bar magnet. III. The north magnetic pole and geographic north are located at exactly the same point. IV. The earth's magnetic field is constant and never changes. I only I and II only III only All of the above.

B

Which of the rays in the diagram could not be used to locate the image by the method of ray tracing? Rays 3 and 4 All the rays could be used to locate the image Ray 3 Rays 2 and 4 Ray 4

B

Which statements explain the behavior of light in this demonstration?I The light undergoes total internal reflection in the stream of water in the same fashion as it does in a fiber optic cable.II Most of the light remains in the stream of water as it does in a fiber optic cable.III Total internal reflection only works with specific frequencies of light. I only I and II II and III I, II and III

B

You are using a small telescope to view two closely spaced light bulbs located a mile away. Each light bulb is emitting blue light. At this distance, the light bulbs are still too close together for you to distinguish them as separate bulbs. If they were emitting red light instead, would you have a better or worse chance of distinguishing them as separate bulbs? Better Worse The color of light would make no difference.

B

A compass is placed in a magnetic field, and the compass needle is oriented as shown in the figure (up). What is the direction of the magnetic field at the location of the compass? Left Right Up Down

C

A section of the surface of a hollow sphere has a radius of curvature of 0.60 m, and both the inside and outside surfaces have a mirror-like finish. What are the focal lengths of the inside and outside surfaces? +0.6 m and -0.6 m -0.6 m and +0.6 m +0.3 m and -0.3 m -0.3 m and +0.3 m

C

For specular reflection from a smooth surface, the angle of incidence measured relative to the normal to the surface ... must always be equal to 90o. must always be equal to zero. will be equal to the angle of reflection as measured relative to the normal to the surface. will be unequal to the angle of reflection as measured relative to the normal to the surface

C

How does the critical angle (θc) for total internal reflection change when ratio between indices of refraction n2/n1 of the two media decreases? It does not change. It gets larger (relative to the normal) It gets smaller (relative to the normal)

C

If 2.0 C of charge passes through a wire in time 0.25 s, what is the current in the wire? 0.50 A 0.50 V 8.0 A 8.0 V

C

Incident light moves through liquid water (n= 1.33) and passes through an interface between water and glass (n= 1.52) at some angle other than the normal to the interface. Which of the following is true of the refracted beam? It does not deviate from the incident path. It bends away from the normal to the interface. It bends towards the normal to the interface.

C

Light from a laser pointer is goes through a window composed of crown glass, which has an index of refraction of n= 1.523. What is the speed of the light while it is in the window glass? 4.57 × 108 m/s 3.00 × 108 m/s 1.97 × 108 m/s 1.52 × 108 m/s

C

Red and green laser light is shined through the same double slit. Each color produces a central bright fringe. Which of the following is true? The width of the central bright fringe for the red light is less than the width for the green light. The width of the central bright fringe for the red and green light is equal. The width of the central bright fringe for the red light is greater than the width for the green light.

C

Suppose that a current I flows through a single-loop circuit containing a battery (voltage V) and a resistor (resistance R). What parameter changes below would reduce the current to half of its original value? Change voltage from V to 2V Set resistance to R/2 Set resistance to 2R None of the above

C

Suppose the human body has a resistance of 500 Ω. How much voltage would be required in order for a life-threating amount of current (0.15 A) to flow through the body? 440 V 220 V 75 V 110 V

C

Suppose you hold up a small convex mirror in front of your face. Which answer describes the image of your face? Real, reduced in size Virtual, inverted Virtual, upright Virtual, enlarged Real, inverted

C

The 110 V provided by common wall sockets in the United States is given as a root-mean-square (rms) voltage. What is the peak value of the voltage? V0= 78.0 V V0= 220 V V0= 155 V V0= 110 V

C

The drawings show two examples in which a ray of light is refracted at the interface between two liquids. In each example the incident ray is in liquid A and strikes the interface at the same angle of incidence. In one case the ray is refracted into liquid B, and in the other it is refracted into liquid C. The dashed lines denote the normals to the interfaces. Rank the indices of refraction of the three liquids in descending order (largest first). nA, nC, nB nA, nB, nC nC, nA, nB nB, nA, nC nC, nB, n

C

The figure shows a mass spectrometer that is calibrated to detect a particular charged particle whose mass is m1 (path 1)? If the charged particles traveling along path 2 are an isotope of those traveling along path 1, how does the mass of particle 2 compare to the mass of particle 1? m1>m2 m1=m2 m1<m2

C

The figure shows three identical charged particles moving with the same speed but at different directions in a uniform magnetic field. Rank the charges in order of the magnetic force each one experiences, starting with the largest. 1: 45 degree angle 2: straight up 3: straight to the right 3, 2, 1 3, 1, 2 2, 1, 3 1, 2, 3

C

The radial lines pointing outward away from the wave source and perpendicular to the wave fronts are called? A. Light vectors B. Light lines C. Rays D. Arrows

C

Three resistors of values 22 Ω, 47 Ω, and 68 Ω are connected in series with a 24-V battery. What is the power dissipated by the 47-Ω resistor? 8.5 W 25 W 1.4 W 4.4 W

C

Two pieces of the same glass are covered with thin films of different materials. In reflected sunlight, however, the films have different colors. Why? The films could have the same thickness, but different refractive indices. The films could have different thicknesses, but the same refractive indices. Both of the preceding answers could be correct.

C

Two waves have amplitudes of 10 m and 7 m, respectively. What are the maximum and minimum amplitudes of the resultant wave if they interfere first constructively, and then destructively? 10 m and 3 m 70 m and 1.4 m 17 m and 3 m 17 m and 0 m

C

What component of a DC electric motor ensures that the current is always in the proper direction to yield a torque that produces a continuous rotation of the coil? The shaft The brushes The split-ring commutator

C

What is true of the image formed by a diverging lens when the object is placed far away? The image is much smaller than the object, real, and located near the focus on the opposites side of the lens as the object. The image is much smaller than the object, real, and located near the focus on the same side of the lens as the object. The image is much smaller than the object, virtual, and located near the focus on the same side of the lens as the object. The image is much smaller than the object, virtual, and located near the focus on the opposites side of the lens as the object.

C

When a resistor is wired in a single loop with a battery, the current through the resistor is I. What is the current through the circuit if you wire three more identical resistors in parallel with the first one? (1/3)I 3I 4I It is the same (I).

C

When someone looks into a concave mirror from a distance of 25 cm, a virtual image is produced that is enlarged by a factor of 2. What is the image distance? -25 cm 50 cm -50 cm 100 cm -100 cm

C

Which statement regarding real and virtual images is correct? A virtual image is always inverted relative to the object, whereas a real image is never inverted. A virtual image is always larger than the object, whereas a real image is always smaller. Rays of light emanate from a real image, but only appear to do so from a virtual image. Rays of light emanate from a virtual image, but only appear to do so from a real image. A virtual image is always smaller than the object, whereas a real image is always larger.

C

An incident beam of light travels through glass (n= 1.52) and impinges upon an interface with liquid water (n= 1.33). What is the critical angle (θc) for total internal reflection at the interface (i.e., with respect to the surface normal)? 45.0o 0o 29.0o 61.0o

D

An object is placed in front of a spherical mirror and its magnification is -6. Which of the following properties is/are true? I. The image is real. II. The image is virtual. III. The image is upright. IV. The image is inverted. V. The image is enlarged. VI. The image is reduced. VII. The image is formed by a concave spherical mirror. VIII. The image is formed by a convex spherical mirror. I, II, III, and VII II, IV, V, VIII I, IV, V, and VIII I, IV, V, and VII II, IV, V, VII

D

At a distance of 2.5 cm from a long straight current-carrying wire, the magnetic field has a value of 1.3 T. What would be the value of the magnetic field at a point that is twice as far from the wire, when the wire carries twice as much current? 2.6 T 0.7 T 5.2 T 1.3 T

D

In this demonstration a laser beam is aimed toward a hole in the side of a soda bottle, out of which a stream of water flows. Which of the following diagrams best illustrates the path of the laser beam? A: laser goes straight through B: laser curves with the flow of water C: refraction in the bottle D: up and down in the flow of water

D

Suppose the rms voltage is 110 V in a single-loop circuit that contains a resistor R= 22 Ω. What is the average power dissipated by the resistor in this circuit? 2420 W 390 W 776 W 550 W

D

The colored bands of light in a rainbow are produced by the scattering of sunlight as it passes through the raindrops. sunlight reflecting off the raindrops. sunlight refracting in the raindrops. interference pattern of sunlight caused by the raindrops.

D

The drawings show (in cross section) two solid spheres and two spherical shells. Each object is made from copper and has a net charge, as the plus and minus signs indicate. Which drawing correctly shows where the charges reside when they are in equilibrium? B: + signs all over middle C: - signs around middle hole A: - signs all over the circle D: + signs on the outside of circle, hole in middle

D

Which of the following correctly depicts the refraction of light through a prism? A: ROYGBIV straight triangle B: VIBGYOR bent triangle up C: VIBGYOR bent triangle down D: ROYGBIV, bent triangle down

D

Which of the following is/are true? A mass spectrometer has many uses in both physics and chemistry. A mass spectrometer can be used to identify charged particles with different masses. A mass spectrometer takes advantage of the fact that charged particles are deflected into circular trajectories within a magnetic field. All of the above are true.

D

Which one of the following five choices best completes this statement: The fact that the refractive index depends on the wavelength of light is the cause of ______________ dispersion. spherical aberration and chromatic aberration. chromatic aberration. spherical aberration. dispersion and chromatic aberration.

E

The drawing shows a current-carrying wire lying along the x axis. The current I is 3.0 A and flows to the right. The wire is 0.45 m long and situated in a uniform magnetic field B. The magnetic field points along the +z axis and has a magnitude of 2.0 T. What is the magnitude F and direction of the magnetic force exerted on the current?

F=2.7 N -y axis

Suppose a circular coil is placed in a uniform magnetic field B. Which of the following creates the emf of the largest magnitude? a. Keeping the field at value B and rotating the coil so that the normal to the coil's loop area rotates 360o relative to the field direction (i.e., one complete revolution) in 2.0 s. b. Keeping the direction of the field parallel to the normal to the area of the coil and decreasing the field uniformly from B to zero in 2.0 s. c. Doubling the field value from B to 2B in 2.0 s.

a

Suppose that when you move the north pole of a bar magnetic toward a coil it induces a positive current in the coil. The strength of the field produced by an electromagnetic can be controlled electronically. Suppose you place a coil near the north pole of an electromagnet and increase the field while keeping everything stationary. Which one of the following will happen? a. A positive current will be induced in the coil. b. No current will be induced in the coil since there is no relative motion. c. A negative current will be induced in the coil.

a

Suppose the electric field in an electromagnetic wave decreases in magnitude. What happens to the value of the wave's magnetic field? a. The magnetic field will also decrease in magnitude. b. The magnetic field will increase in magnitude. c. The magnetic field will remain constant.

a

Suppose you reduced the frequency of a generator from 60 Hz to 50 Hz to accommodate a European electrical device. What would you need to do in order to keep the peak emf of the generator the same as it had been when operating at 60 Hz? a. Increase the magnetic field strength. b. Decrease the magnetic field strength. c. Decrease the area of the loop. d. Decrease the number of turns. e. Nothing would need to be changed.

a

The figure at the right shows three situations - A, B, and C - in which an observer and a source of electromagnetic waves are moving along the same line. In each case the source emits a wave of the same frequency. The arrows in each situation denote velocity vectors relative to the ground and have magnitudes of either v or 2v. Rank the magnitudes of the frequencies of the observed waves in descending order (largest first). a. B, A, C b. B, C, A c. A, C, B d. A, B, C e. C, A, B

a

What component of a DC electric motor ensures that the current is always in the proper direction to yield a torque that produces a continuous rotation of the coil? a. The split-ring commutator b. The shaft c. The brushes

a

What would happen if you reversed the direction of the magnet in a moving-coil microphone so that the opposite pole were closest to the coil. a. The signal would reverse polarity. b. The signal would become weak. c. There would be no change in the signal.

a

The rechargeable batteries for a laptop computer need a much smaller voltage than what a wall socket provides. Therefore, a transformer is plugged into the wall socket and produces the necessary voltage for charging the batteries. The batteries are rated at 9.0 V, and a current of 198 mA is used to charge them. The wall socket provides a voltage of 120 V. (a) Determine the turns ratio of the transformer. (b) What is the current coming from the wall socket? (c) Find the average power delivered by the wall socket and the average power sent to the batteries.

a. (ns/np) 0.075 no units b. (ip) 0.0149 A c. (Pp) 1.78 W, (Ps) 1.78 W

(a) Neil A. Armstrong was the first person to walk on the moon. The distance between the earth and the moon is 3.85 × 108 m. Find the time it took for his voice to reach the earth via radio waves. (b) Someday a person will walk on Mars, which is 5.60 × 1010 m from the earth at the point of closest approach. Determine the minimum time that will be required for a message from Mars to reach the earth via radio waves.

a. 1.283 s b. 186.7 s

An electromagnetic wave travels in a vacuum. The wavelength of the wave is tripled. How is this accomplished? a. By tripling the frequency of the wave. b. By reducing the frequency of the wave by a factor of three. c. By reducing the speed of the wave by a factor of three. d. By tripling the magnitudes of the electric and magnetic fields that comprise the wave. e. By tripling the speed of the wave.

b

Consider two electromagnetic waves A and B traveling in vacuum, where the frequency of A is twice that of B (fA=2fB). Which of the following is/are true? a. The speed of wave A is ½ the speed of wave B. b. The speed of wave A is equal to the speed of wave B. c. The wavelength of wave A equals the wavelength of wave B. d. The wavelength of wave A is twice the wavelength of wave B. e. The speed of wave A is twice the speed of wave B.

b

If the value of the electric field in an electromagnetic wave were doubled, what would happen to the total energy density of the wave? a. The total energy density would double. b. The total energy density would quadruple. c. The total energy density would decrease by a factor of 2. d. Nothing. It would remain constant. e. The total energy density would increase by 2.

b

The drawing shows four situations A, B, C, and D in which an observer and a source of electromagnetic waves are moving along the same line. In each case the source emits a wave of the same frequency, and in each case only the source or the observer is moving. The arrow in each situation denotes the velocity vector, which has the same magnitude in each situation. When there is no arrow, the observer or the source is stationary. Rank the frequencies of the observed electromagnetic waves in descending order (largest first) according to magnitude. a. C and D (a tie), A and B (a tie) b. B and D (a tie), A and C (a tie) c. B and C (a tie), A and D (a tie) d. A and B (a tie), C and D (a tie) e. A and D (a tie), B and C (a tie)

b

The drawing shows two sheets of polarizing material, which have their transmission axes crossed. The sheet on the left has its transmission axis aligned vertically. Light is incident from the left, as shown and can be either completely unpolarized or completely polarized along the vertical direction. Which one of the following statements is true concerning the light that exits the polarizer on the right? a. Light exits the polarizer on the right for the unpolarized incident light, but not for the polarized incident light. b. No light exits the polarizer on the right for either the unpolarized or the polarized incident light. c. Light exits the polarizer on the right for either the unpolarized or the polarized incident light. d. Light exits the polarizer on the right for the polarized incident light, but not for the unpolarized incident light.

b

True or False: An aluminum can could be picked up by an electromagnetic at a recycling center. a. True b.False

b

Which of the following is/are true? a. The electromagnetic spectrum consists of only visible light. b. The electromagnetic spectrum consists of light with a vast range of frequencies and wavelengths, and visible light only makes up a small fraction of this spectrum. c. Neither of the above statements is correct.

b

Which of the following is/are true? I. The earth has a magnetic field. II. The earth's magnetic field is similar to a bar magnet. III. The north magnetic pole and geographic north are located at exactly the same point. IV. The earth's magnetic field is constant and never changes. a. I only b. I and II only c. III only d. All of the above.

b

Suppose a transformer has 50 windings on its primary and 300 windings on its secondary. If the input voltage (i.e., on the primary) is 40 V, what is the voltage at the output (i.e., on the secondary)? a. 6 V b. 15 kV c. 240 V d. 40 V

c

Suppose that the emf from a rod moving in a magnetic field was used to supply the current to illuminate a light bulb in a circuit, and the force needed to keep the rod moving is F. What happens to the force needed drive the motion of the rod if the light bulb is removed? a. A larger force is needed to the keep the rod moving. b. It is the same as when the bulb is in the circuit. c. No force is needed: there is no longer a magnetic force to oppose the motion

c

Suppose the current through a light bulb in a circuit is provided by the motional emf of a rod moving in a magnetic field. If you wanted to keep the intensity of the light emitted by the bulb constant when the strength of the magnetic field is doubled, how should the speed of the rod be changed? a. The speed of the rod should be doubled. b. The speed of the rod should be squared. c. The speed of the rod should be halved. d. The speed of the rod should not be changed.

c

The drawing shows two sheets of polarizing material, each of which has its transmission axis aligned vertically. Light is incident from the left, as shown, and can be either completely unpolarized or completely polarized along the vertical direction. In either case, the average intensity of the incident light is the same, and light exits the polarizer on the right. Which one of the following statements is true concerning the intensity of the exiting light? a. The intensity of the exiting light is the same for both types of incident light. b. The intensity of the exiting light is greater when the incident light is completely unpolarized. c. The intensity of the exiting light is greater when the incident light is completely polarized.

c

The figure shows a mass spectrometer that is calibrated to detect a particular charged particle whose mass is m1 (path 1)? If the charged particles traveling along path 2 are an isotope of those traveling along path 1, how does the mass of particle 2 compare to the mass of particle 1? a. m1=m2 b. m1>m2 c. m1<m2

c

The figure shows three identical charged particles moving with the same speed but at different directions in a uniform magnetic field. Rank the charges in order of the magnetic force each one experiences, starting with the largest. 1. 45 degree angle, 2. 90 degree angle, 3. 180 degree angle a. 1, 2, 3 b. 3, 1, 2 c. 2, 1, 3 d. 3, 2, 1

c

The same current-carrying wire is placed in the same magnetic field, but in different orientations. Rank the magnetic force on each wire, starting with the largest. A. 45 degree B. 180 degree C. 90 degree a. C, A, B b. A, B, C c. B, A, C d. C, B, A

c

Which of the following does not produce a change in magnetic flux through a square loop of wire? a. The loop falls through a region of zero magnetic field into a region of constant magnetic field. b. The loop falls through a region of constant magnetic field into a region of zero magnetic field. c. The loop falls through a uniform magnetic field without rotating. d. The loop rotates haphazardly while it falls through a uniform magnetic field.

c

An electromagnetic wave is traveling in a vacuum. The electric field E of the wave is doubled. What happens to the magnetic field B, the total energy density u, and the intensity S of the wave? a. B doubles, u decreases by a factor of two, S decreases by a factor of two b. B increases by a factor of four, u increases by a factor of four, S increases by a factor of four c. B doubles, u increases by a factor of four, S doubles d. B doubles, u increases by a factor of four, S increases by a factor of four e. B doubles, u doubles, S doubles

d

Suppose a transformer has 50 windings on its primary and 200 windings on its secondary. If the power input into the primary is 400 W, what is the power output at the secondary? a. 1600 W b. 100 W c. 200 W d. 400 W

d

Suppose you wanted to improve a moving-coil microphone so that it was more sensitive (i.e., so that it outputs a stronger induced emf for a given sound intensity). Which of the following will improve the sensitivity? a. Replace the diaphragm with one that moves more easily. b. Replace the magnet with a stronger one. c. Increase the coil with one with more turns. d. All of the above. e. None of the above.

d

Vertically polarized light with an average intensity of S0 is incident on a polarizer whose transmission axis makes an angle of 30o with respect to the horizontal. What is the average intensity of the light that is transmitted through the polarizer? a. S0 b. 0 c. S0/2 d. So/4

d

What is the wavelength of red light in vacuum that has a frequency of 4.00 × 1014 Hz? a. 650 nm b. 1250 nm c. 425 nm d. 750 nm

d

Which of the following is/are true? a. A mass spectrometer has many uses in both physics and chemistry. b. A mass spectrometer can be used to identify charged particles with different masses. c. A mass spectrometer takes advantage of the fact that charged particles are deflected into circular trajectories within a magnetic field. d. All of the above are true.

d

Which of the following will increase the peak emf in an AC generator without changing the frequency? a. Replace the magnet with a stronger one (increase the magnetic field strength). b. Replace the coil with one with more turns. c. Increase the coil with one with a larger area. d. All of the above. e. None of the above.

d

Who is credited for developing the wave theory of electromagnetism? a. Michael Faraday b. Sir Isaac Newton c. Galileo Galilee d. James Clerk Maxwell

d

Which of the following would increase the torque on a current-carrying loop of wire placed in a magnetic field? a. Increase the number of turns in the loop. b. Increase the cross-sectional area of each loop. c. Increase the strength of the magnetic field. d. Rotate the loop so that the normal to the loop's surface is perpendicular to the magnetic field. e. All of the above.

e

A diffraction grating has 45,000 slits/cm. What is the distance between adjacent slits? 1.0 cm 2.2 cm 2.2 × 10-5 cm None of these.

C

The thickness (t) of the pits in a CD track is chosen to be equal to which of the following? 2t=λcoating/4 t=λcoating 2t=λcoating/2 2t=λcoating

C

Three point charges have equal magnitudes and are located on the same line. The separation d between A and B is the same as that between B and C. One of the charges is positive and two are negative, as the drawing shows. Consider the net electrostatic force that each charge experiences due to the other two charges. Rank the net forces in descending order (greatest first) according to magnitude. A, C, B C, A, B B, A, C A, B, C B, C, A

C

When the demonstrator moves the lens upward, the image will becomes sharper. move downward. move upward. not move.

C

If the speed of light in some unknown material is 2.00 × 108 m/s, what is the index of refraction of the medium? 2.00 0.67 1.88 1.50

D

Which of the following colored bands can be explained in the same fashion as one explains the colored bands of rainbows?I oil slicksII soap filmsIII butterfly wings I only I and II All of them can be explained this way. None of them can be explained this way.

D

A long, straight wire carries a current in a direction from left to right as shown in the figure. Point P is located above the wire in the plane of the screen. What is the direction of the magnetic field at point P? Left Into the screen Right Up Out of the screen Down

E

Rays of light coming from the sun (a very distant object) are near and parallel to the principal axis of a concave mirror. After reflecting from the mirror, where will the rays cross each other at a single point? The rays __________ will cross at the point where the principal axis intersects the mirror. will cross at a point beyond the center of curvature. will cross at the center of curvature. will not cross each other after reflecting from a concave mirror. will cross at the focal point.

E

The drawing shows four situations in which two very long wires are carrying the same current, although the direction of the currents may be different. The point P in the drawings is equidistant from each wire. Which one (or more) of these situations gives rise to a zero net magnetic field at P? 1: top right, bottom left 2: top right, bottom right 3: top right, down 4: top right, up Only 1 Only 2 2 and 3 3 and 4 2 and 4

E

Which of the following would increase the torque on a current-carrying loop of wire placed in a magnetic field? Increase the number of turns in the loop. Increase the cross-sectional area of each loop. Increase the strength of the magnetic field. Rotate the loop so that the normal to the loop's surface is perpendicular to the magnetic field. All of the above.

E

Suppose you are standing in front of a concave spherical mirror. Which of the following image properties are possible? Your image is upright. Your image is inverted. Your image is enlarged. Your image is reduced. Your image is real. Your image is virtual. All of the above.

G

A changing magnetic field induces an emf of 5.0 V in a single-loop of wire. Suppose the single loop were replaced by one continuous wire wrapped to form a coil of five loops, each with the same size and shape as the original loop, and placed in the same changing magnetic field and with the same orientation as the single loop. What would be the magnitude of the induced emf in the coil? a. 25 V b. 5.0 V c. 0 V d. 1.0 V

a

A current carrying wire is experiencing a magnetic force in a magnetic field. What happens to the direction of the magnetic force on the wire, if the current in the wire is reversed? a. The magnitude of the force remains unchanged, but it reverses direction. b. The magnitude of the force remains unchanged, but it is oriented perpendicular to the direction of the original force. c. The magnitude of the forces decreases, but it remains in the same direction. d. Nothing. The magnitude and direction of the force remain unchanged.

a

A long, straight wire carries a current in a direction from left to right as shown in the figure. Point P is located above the wire in the plane of the screen. What is the direction of the magnetic field at point P? a. Out of the screen b. Right c. Up d. Down e. Left f. Into the screen

a

A uniform magnetic field is oriented vertically upward in large rectangular region of space, and the field is zero everywhere else. A circular loop is launched horizontally so that the normal to the loop's area is also vertical, and the loop travels from a region of zero field into the region of the vertical field. Looking at the loop from the top, in which direction is the induced current? a. Clockwise b. Counterclockwise c. There is no induced current

a

An electromagnetic wave is traveling in a vacuum. The magnitudes of the electric and magnetic fields of the wave are _____________, and the electric and magnetic energies carried by the wave are _____________. a. proportional (but not equal) to each other, equal b. proportional (but not equal) to each other, unequal c. equal, proportional (but not equal) to each other d. equal, equal

a

Suppose that a magnet and a coil were dropped together from the same height at the same time. Would there be an induced current in the coil? a. No, because, as they fall together, they are not moving relative to each other. b. Yes, since they are both moving.

a

An object carries a charge of -7.0 µC, while another carries a charge of -2.0 µC. How many electrons must be transferred from the first to the second object so that both objects have the same charge?

# electrons=1.56e13 no units

During a particular thunderstorm, the electric potential between a cloud and the ground is Vcloud - Vground = 2.9 x 108 V, with the cloud being at the higher potential. What is the change in an electron's potential energy when the electron moves from the ground to the cloud?

-4.64e-11 J

In the operating room, anesthesiologists use mass spectrometers to monitor the respiratory gases of patients undergoing surgery. One gas that is often monitored is the anesthetic isoflurane (molecular mass = 3.06 × 10-25 kg). In a spectrometer, a single ionized molecule of isoflurane (charge = + e) moves at a speed of 6.56 × 103 m/s on a circular path that has a radius of 0.178 m. What is the magnitude of the magnetic field that the spectrometer uses?

0.07 T

Two wires are identical, except that one is aluminum and one is copper. The aluminum wire has a resistance of 0.328Ω. What is the resistance of the copper wire? Take the resistivity of copper to be 1.72 x 10-8 Ω·m, and that of aluminum to be 2.82 x 10-8 Ω·m.

0.200 ohms

An electric field of 170000 N/C points due west at a certain spot. What is the magnitude of the force that acts on a charge of -5.6C at this spot?

0.95 N

Magnetic resonance imaging (MRI) is a medical technique for producing "pictures" of the interior of the body. The patient is placed within a strong magnetic field. One safety concern is what would happen to the positively and negatively charged particles in the body fluids if an equipment failure caused the magnetic field to be shut off suddenly. An induced emf could cause these particles to flow, producing an electric current within the body. Suppose the largest surface of the body through which flux passes has an area of 0.024 m2 and a normal that is parallel to a magnetic field of 1.2 T. Determine the smallest time period during which the field can be allowed to vanish if the magnitude of the average induced emf is to be kept less than 0.014 V.

2.06 s

The capacitance of an empty capacitor is 6.70 μF. The capacitor is connected to a 12-V battery and charged up. With the capacitor connected to the battery, a slab of dielectric material is inserted between the plates. As a result, 9.00 × 10-5 C of additional charge flows from one plate, through the battery, and onto the other plate. What is the dielectric constant of the material?

2.12 no units

Intelligent beings in a distant galaxy send a signal to earth in the form of an electromagnetic wave. The frequency of the signal observed on earth is 1.5% greater than the frequency emitted by the source in the distant galaxy. What is the speed vrel of the galaxy relative to the earth?

4.5e6 m/s

There are approximately 114 million TVs in the United States. Each uses, on average, 79 W of power and is turned on for 6.3 hours a day. If electrical energy costs 0.10 dollars per kWh, how much money is spent every day in keeping the TVs turned on?

5.67e6 dollars

A conducting rod is moving through a magnetic field, as in the drawing. The magnetic field strength is 0.65 T, and the speed of the rod is 4.8 m/s. Suddenly, the field strength decreases to 0.48 T. To what value must the speed v of the rod be adjusted to reestablish the emf induced between the ends of the rod at its initial value?

6.5 m/s

The drawing shows an electron entering the lower left side of a parallel plate capacitor and exiting at the upper right side. The initial speed of the electron is 4.41 × 106 m/s. The capacitor is 2.00 cm long, and its plates are separated by 0.150 cm. Assume that the electric field between the plates is uniform everywhere and find its magnitude.

830 N/C

A circuit is composed of a 12.0 V battery and a 110 Ω resistor. What is the power dissipated by the resistor? 1.3 W 0.11 A 0.11 W 1.3 A

A

Which of the following statements is true?I When sunlight passes through a convex lens, the hottest spot is located at its focal point.II To create an inverted image, place the object between a convex lens and its focal point.III When using a magnifying glass, the sharpest image occurs when the object is placed at its focal point. I only II only III only All the statements are true

A

Which one of the following statements concerning spherical mirrors is correct? Only a concave mirror can produce an enlarged image, provided the object distance is less than the radius of curvature. Only a concave mirror can produce an enlarged image, provided the object distance is greater than the radius of curvature. Both concave and convex mirrors can produce an enlarged image. Only a convex mirror can produce an enlarged image.

A

A circular loop of wire is positioned so the normal to its area points vertically upward. A bar magnet is dropped from above the loop so that its north pole falls through the loop first. When looking at the loop from above, in which direction is the induced current in the loop just as the north pole of the magnet enters the loop? a. Clockwise b. Counterclockwise c. There is no induced current

b

A positive charge is moving with velocity v through a region of space where a uniform magnetic field exists everywhere into the screen, as the figure shows. What is the direction of the magnetic force on the charge just as it enters the field? a. Downward b. Upward c. Out of the screen d. Right e. Left f. Into the screen

b

A proton is released from rest at a location in space where the magnetic field points upward toward the top of the page. Which of the following is true? a. The proton experiences a magnetic force to the right. b. The proton experiences no magnetic force and remains at rest. c. The proton experiences a magnetic force upward. d. The proton experiences a magnetic force downward.

b

An astronomer observes that the wavelength of light from a distant star is shifted toward the red part of the visible spectrum. Which of the following is true? a. The distance between the earth and the star is decreasing. b. The distance between the earth and the star is increasing. c. The distance between the earth and the star is remaining constant.

b

The figure shows three particles with identical charge magnitudes and masses moving through a uniform magnetic field inside a bubble chamber. Which particle has the greatest speed? particle 1 and 2 in circles, 3 going out a. 2 b. 3 c. 1

b

True or False: A piece of unmagnetized iron, with randomly oriented magnetic domains, would not be attracted to a permanent magnet. a. True b. False

b

A compass is placed in a magnetic field, and the compass needle is oriented as shown in the figure (up). What is the direction of the magnetic field at the location of the compass? a. Down b. Left c. Right d. Up

d

At a distance of 2.5 cm from a long straight current-carrying wire, the magnetic field has a value of 1.3 T. What would be the value of the magnetic field at a point that is twice as far from the wire, when the wire carries twice as much current? a. 5.2 T b. 2.6 T c. 0.7 T d. 1.3 T

d

You have three light bulbs; bulb A has a resistance of 240 Ω, bulb B has a resistance of 192 Ω, and bulb C has a resistance of 144 Ω. Each of these bulbs is used for the same amount of time in a setup like that in the drawing. In each case the speed of the rod and the magnetic field strength are the same. Rank the setups in descending order, according to how much work the hand in the drawing must do (largest amount of work first). a. B, A, C b. A, C, B c. B, C, A d. C, B, A e. A, B, C

d

An olive is at the bottom of a glass of alcohol (n = 1.36), 5.73 cm beneath the surface. Above the alcohol is air. To a person in the air, who is directly above the olive, what is the apparent depth d' of the olive.

d1=4.21 cm

Two polarizers are crossed, as shown in the figure. Which of the following situations would allow light to be transmitted through both polarizers? a. Shine unpolarized light through polarizer 1. b. Shine unpolarized light through polarizer 2. c. Shine vertically polarized light through polarizer 1. d. Shine horizontally polarized light through polarizer 2. e. None of these would result in light being transmitted through both polarizers.

e

Which of the following is/are true? a. Electromagnetic waves are created by accelerating charges. b. Electromagnetic waves are transverse waves. c. Electromagnetic waves consist of time-varying electric and magnetic fields that are mutually perpendicular. d. Electromagnetic waves move at the speed of light in a vacuum. e. All of the above are true.

e

A circular coil of N turns rotates at some frequency in a constant magnetic field and produces an emf. Which of the following will double the emf? a. Double the field. b. Double the frequency. c. Double the area of the coil. d. Double the number of turns of the coil. e. None of the above. f. Any one of the above.

f

Resistors R1= 22 Ω and R2= 47 Ω are wired in parallel with a battery of voltage V= 12.0 V. R2 is now replaced by a wire. What is the current through R1? 0.55 A 0 A 0.23 A 3.1 A

B