Phy 104 final

The 200-inch-diameter concave mirror of the Hale telescope on Mount Palomar has a focal length of 16.9 m. An astronomer stands 35.0 m in front of this mirror. What is the magnification of her image?

-0.934

The figure shows a circuit with an area of 0.072 m2 containing a R = 3.2-Ω resistor and a C = 120- μF uncharged capacitor. Pointing into the plane of the circuit is a uniform magnetic field of magnitude 0.30 T. In 0.010 s the magnetic field strengthens at a constant rate to become 1.2 T pointing into the plane. What maximum charge (sign and magnitude) accumulates on the upper plate of the capacitor in the diagram?

-780 μC

A convex mirror on the passenger side of a car produces an image of a vehicle that is 11.3 m from the mirror. If the image is located 38.6 cm behind the mirror, what is the radius of curvature of the mirror?

-80 cm

A portable CD player operates with a current of 20 mA at a potential difference of 6.2 V. What is the power usage of the player?

0.124 W

An aluminum wire is 1.3 m long and has a diameter of 0.05 cm. What is the resistance of the wire?

0.18 Ω

A charge of +3q sits at the origin. A charge of -5q sits on the x-axis at the 1.00 m mark. Given that q=4.11 x 10-9 C, at what location on the x-axis is the electric potential zero?

0.375 m

When an electromagnetic wave travels from one medium to another with a different speed of propagation, the frequency of the wave remains the same. Consider a case where the wave speed decreases from c to 0.45 c. By what factor does the wavelength change?

0.45

A compound microscope has the objective and eyepiece mounted in a tube that is 20.0 cm long. The focal length of the eyepiece is 2.18 cm, and the near-point distance of the person using the microscope is 31.0 cm. If the person can view the image produced by the microscope with a completely relaxed eye, and the magnification is -3500, what is the focal length of the objective?

0.724 mm

A parallel plate capacitor has plates with an area of 0.019 m2 and a separation of 0.72 mm. The space between the plates is filled with a dielectric whose dielectric constant is 2.4. What is the potential difference between the plates when the charge on the capacitor plates is 5.8 μC?

1.0 x 104 V

Magnesium fluoride (n=1.38) is frequently used as a lens (n=1.50) coating to make nonreflecting lenses. What is the difference in the minimum film thickness required for maximum transmission of green light (lambda=520 nm) and yellow light (lambda=580 nm)?

1.09x10^{-8} m

Find the current in resistor R3.

1.25 A

A 12-V battery is connected to four capacitors in series. The capacitors have the following capacitances: 9 μF, 12 μF, 32 μF, and 42 μF. Find the voltage across the 32 μF capacitor.

1.5 V

What is the equivalent resistance in the following arrangement of resistors? (R1=3.0 ohms, R2=3.0 ohms, R3=4.0 ohms, R4=4.0 ohms)

1.5 ohms

A system of 1728 particles, each of which is either an electron or a proton, has a net charge of +3.552 x 10-17 C. What is the mass of this system?

1.629 x 10-24 kg

Laser light with a wavelength λ = 633 nm illuminates a pair of slits at normal incidence. What slit separation will produce first-order maxima at angles of ± 22.0 degrees from the incident direction?

1.69 μm

A cell membrane is 8.7 nm thick and has an electrical resistivity of 1.3 x 107 Ωm. If the potential difference between the inner and outer surfaces of a cell membrane is 63 mV, how much current flows through a circular patch of membrane with radius 1.0 μm?

1.8 x 10-12 A

A horizontal beam of light enters a 45-90-45-degree prism at the center of its long side, as shown in the figure. The emerging ray moves in a direction that is 43 degrees below the horizontal. What is the index of refraction of this prism?

1.82

The average diameter of the eye's pupil during the day is 4.0 mm. What is the minimum angle of separation for two 600 nm sources from which light passes through the pupil of the eye?

1.83x10^(-4) radians.

A disk drive plugged into a 120-V outlet operates on a voltage of 6.0 V. The transformer that powers the disk drive has 200 turns on its primary coil. Find the number of turns on its secondary coil.

10

You have a semicircular disk of glass with an index of refraction n = 1.43. Find the incident angle θ for which the beam of light in the figure will hit the indicated point on the screen.

11.7 degrees

A circular coil of wire has a radius of 6.30 cm and has 215 turns of wire that carries 5.90 A of current. What is the magnetic field at the center of the coil?

12.7 mT

A proton has an initial speed of 4.90 x 105 m/s. What potential difference is required to bring the proton to rest?

1250 V

An object with a height of 4.67 cm is placed 48.2 mm to the left of a converging lens with a focal length of 36.0 mm. Find the height and orientation of the image.

13.8 cm, inverted

A single conducting loop of wire has an area of 4.8 x 10-2 m2 and a resistance of 97 Ω. Perpendicular to the plane of the loop is a magnetic filed of strength 1.1 T. At what rate must this field change if the induced current in the loop is to be 0.64 A?

1300 T/s

A 100-W lightbulb operates on a potential difference of 120 V. Find the resistance of the bulb.

144 Ω

Consider the long, straight current-carrying wires shown in the figure. One wire carries a current I1 = 4.5 A in the positive x-direction; the other wire carries a current I2 = 3.2 A in the negative y-direction. Calculate the net magnetic field at point A.

15 μT, into the page (-z-hat)

The resistor in an RC circuit has a resistance of 110 Ω and a time constant of 1.9 ms. Calculate the current in the circuit 7.6 ms after the switch is closed. Assume that the capacitor is initially uncharged and that the emf of the battery is 12.0 V.

2 mA

Two point charges, the first with a charge of +4.47 x 10-6 C and the second with a charge of +1.86 x 10-6 C, are separated by 17.4 mm. What is the magnitude of the electrostatic force experienced by charge 2?

247 N

A student has a lens with focal length f = 11 cm. Find the maximum magnification produced by this lens.

3.3

A 9.0-V battery is connected across the terminals A and B for the group of resistors shown in the figure. What is the potential difference across R2?

3.6 V

Reading glasses with a power of +1.75 diopters make reading a book comfortable for you when you wear them 1.90 cm from your eye. If you hold the book 22.0 cm from your eye, what is your near point distance?

32.9 cm

A physics student uses a converging lens with a focal length of 0.05 m to read a small measurement scale. What is the magnification for viewing of the relaxed eye? Assume the near point distance is 20 cm.

4

What is the magnitude of the magnetic force exerted on a 4.67-m length of wire carrying a current of 2.38 A perpendicular to a magnetic field of 0.385 T?

4.28 N

Approximating the eye as a single thin lens 2.35 cm from the retina, find the eye's near-point distance if the smallest focal length the eye can produce is 2.22 cm.

40.1 cm

A soap film (n = 1.33) is 625 nm thick. White light strikes the film at normal incidence. What visible wavelengths will be constructively reflected if the film sits on a surface of magnesium fluoride (n = 1.38). Visible light has vacuum wavelengths between 400 nm (violet) and 700 nm (red).

416 nm and 554 nm

An array of solar panels produces 8.65 A of direct current at a potential difference of 148 V. The current flows into an inverter that produces 60-Hz alternating current with Vmax = 84.8 V and Imax = 14.7 A. What is the power efficiency of the converter?

48.7%

Find the frequency of yellow light with a wavelength of 590.0 nm.

5.08 x 1014 Hz

How rapidly does the distance between you and your mirror image decrease if you walk toward a mirror at a speed of 3.1 m/s and an angle of 26 degrees to its normal?

5.6 m/s

Blue light (λ = 420 nm) strikes a single slit at normal incidence. What slit width will produce a central maximum that is 2.27 cm wide on a screen 1.55 m from the slit?

57.4 μm

A circular coil with a diameter of 23.4 cm and 210 turns rotates about a vertical axis with an angular speed of 1750 rpm. The only magnetic field in this system is that of the Earth. A the location of the coil, the horizontal component of the magnetic field is 3.65 x 10-5 T, and the vertical component is 2.97 x 10-5 T. Find the maximum emf induced in the coil.

60.3 mV

Unpolarized light passes through two polarizers whose transmission axes are at an angle of 42.0 degrees with respect to each other. What fraction of the incident intensity is BLOCKED by the polarizers?

72.4 %

Standing 1.8 m in front of a small vertical mirror, you see the reflection of your belt buckle, which is 0.63 m below your eyes. What angle do your eyes make with the horizontal when you look at the belt buckle?

9.9 degrees

A 8.45-μC particle with a mass of 6.15 x 10-5 kg moves perpendicular to a 0.493-T magnetic field in a circular path of radius 34.1 m. How much time will it take for the particle to complete one orbit?

92.7 s

A certain farsighted person has a near point of 75 cm. Which type of lens should an optometrist prescribe to see objects as close as 20 cm?

A converging lens with power=+3.66 D.

Since they diffract around normal, meter-sized objects, cell phone radio waves must be much shorter than one meter.

False

The final image formed by two converging lenses is virtual.

False

To get destructive interference with a non-reflective coating on a glass surface, the light has to travel an extra distance in the coating equal to one quarter of a wavelength.

False

Two lenses that are 42 cm apart are used to form an image. Lens 1 is diverging and has focal length f1 = -8.0 cm; lens 2 is converging and has focal length f2 = 20 cm. The object is placed 13 cm to the left of lens 1. Draw a ray diagram for this situation and use your results to choose the correct description of the image.

Image is real and inverted.

Polarizer A is set up so that its polarization direction is vertical. Polarizer B is set up so that its polarization direction is 45 degrees from vertical. Which of the following describes light that has passed through both filters?

It is less intense than the original light and is polarized 45 degrees from vertical.

Imagine two RC circuits labelled A and B. The resistors in the two circuits are identical, but the capacitor in circuit B has a capacitance twice as large as the capacitor in circuitA (CB=2 CA). If each capacitor is initially fully charged, which capacitor will discharge to 37% of its maximum voltage first?

The capacitor in circuit A because the time constant will be smaller.

Two polarizers are set up so that their polarization directions are parallel and vertical. Which of the following describes light that has passed through both filters?

The light is polarized in the vertical direction.

A positively charged particle enters the magnetic field region of a mass spectrometer and turns to the right. What would happen to an equal-mass particle with a negative charge of equal magnitude?

The negative charged particle would turn to the left..

For a soap bubble, light reflecting from the outer surface of the bubble undergoes a phase shift of 180-degrees.

True

Rayleigh scattering predicts that the scattering of light is greater for light with short wavelengths.

True

The angular magnification relates the angular size of an object at some location to the angular size of the image formed by a lens at the same location.

True

During any complete cycle in which the initial EMF is zero, the EMF of an AC generator becomes zero again at

a time equal to one-half of the total period.

An electric charge on the z axis oscillates sinusoidally about the origin. A distant observer is located at a point on the +x axis. At the observer's location, what are the directions of a) the electric field oscillation, b) the magnetic field oscillation, and c) the electromagnetic wave propagation?

a) z-direction, b) y-direction, c) +x-direction

An interference pattern is produced by

at least two coherent sources of light.

Destructive interference occurs when

at least two light waves cancel each other at some location.

Generators work because a) the ends of the loop are connected to an external circuit. b) the rotating armature changes the area of the loop perpendicular to the magnetic field direction. c) the magnetic field pushes the armature around, generating current (not this one). d) the rotating armature causes centripetal forces that cause currents.

b I think

For a fixed screen distance, increasing the width of a single diffraction slit for light of a single wavelength

decreases the spacing between dark fringes.

An object with a charge of +6.3 μC and a mass of 0.073 kg experiences an upward electric force, due to a uniform electric field, equal in magnitude to its weight. If the electric charge on the object is reduced by a factor of one-third while its mass remains the same, find the direction and magnitude of its acceleration.

down at 6.5 m/s2

People who are near-sighted

have far points closer than infinity.

To study wave interference, a student uses two speakers driven by the same sound wave of wavelength 0.3 m. If the distances from a point to the speakers differs by 0.45 m, the waves will

interfere destructively.

The total magnification of a compound microscope

is equal to the product of the magnifications of the objective and eyepiece lenses.

In a compound microscope, the image formed by the objective lens

is usually very near the focal point of the eyepiece lens.

two sources of light send waves through a single slit. The images are resolvable

it the central bright spots of the individual diffraction patterns do not overlap

A double convex lens

makes parallel light rays converge at the focal point.

For a telescope, the fact that light enters the objective lens parallel to the optical axis

means that the objective image is formed at the focal point of the objective lens.

if the potential increases most rapidly in the positive y-direction, the electric field points in the

negative y-direction.

In a motor, back EMF increases as

the armature loop increases its angular speed.

Sunrises and sunsets appear to be orange-red because light travels through more atmosphere at those times and

the blue light gets scattered away from our line of sight.

Two identical waves destructively interfere when

the crests of one wave occur at the same location as the troughs of the other.

The torque on a current-carrying loop is maximum when

the magnetic moment is perpendicular to the magnetic field direction.

For human vision, the near point is

the point closest to the eye at which objects can be seen clearly.

An equipotential surface is

the set of locations where the electric potential is constant.

In the two-slit experiment, a bright interference fringe is produced on a screen when

the two light waves travel distances that are different by any whole (integer) number of wavelengths.

A light wave travels in a medium with an index of refraction n1. It reflects from the surface of a medium with an index of refraction of n2. If n2 > n1, then

the wave undergoes a 180-degree phase change.

If a loop of wire is stretched in a direction perpendicular to the direction of a constant, uniform magnetic field,

then an induced current will run through the loop because the loop encloses a varying number of magnetic field lines.

Two point charges lie on the x axis. A charge of -2.3 x 10-6 C is at x=-5 cm, and a charge of +9.2 x 10-6 C is at x=12 cm. At what position x would a third positive charge be in equilibrium?

x=-22 cm