PHYS 1002 - Final Exam

1.4 A

(All parameters the same as in the previous question) In the diagram below, the magnetic field has an initial magnitude of 0.26 T, the width and height of the single loop of wire are 9.5 cm and 5.6 cm respectively, and the resistance is 0.88 mΩΩ. If the magnetic field strength decreases steadily to zero in 1.1 seconds, what will be the magnitude of the induced current in the loop as this occurs?

increases

(choose from the available options to fill in the blank) In a charging RC circuit, the voltage across the capacitor plates generally __________ as time goes by.

decreases

(choose from the available options to fill in the blank) In a discharging RC circuit, the current generally __________ as time goes by.

−−0.10 J

A +3.5 μμC point charge is situated 37 cm away from a −−1.2μμC point charge. What is the electric potential energy of this system (relative to zero if the charges were infinitely far apart)? (μμ = 10-6)

20.9∘∘

A beam of light in air enters a glass slab with an index of refraction of 1.40 at an angle of incidence of 30∘∘. What is the angle of refraction?

7.2 x 10−−11 J

A capacitor with a plate separation of 0.75 mm has a capacitance of 4.0 pico farads (pico = 10−−12 ). If this capacitor is connected to a 6.0 V battery, how much energy is stored in the capacitor? (You may or may not need all of the information given.)

8.0 x 103 V/m

A capacitor with a plate separation of 0.75 mm has a capacitance of 4.0 pico farads (pico = 10−−12 ). If this capacitor is connected to a 6.0 V battery, what will be the electric field magnitude between the plates? (You might not need all of the information given.)

6.68 x 1014 Hz

A certain star moves away from our solar system with a relative speed of 550 km/s. If the star emits light at a frequency of 6.69 x 1014 Hz, at what frequency would that light be detected here on Earth?

to the right

A current I in a straight section of wire flows into the page as shown below. In which direction would the magnetic field due to this current point at a location directly above the wire?

1.67 x 10−−6 m

A diffraction grating has a line density of 600 lines per millimeter. What is the distance between lines?

+1.3 D

A farsighted individual has a near point of 37 cm. What refractive power corrective contact lens will be required to give them normal vision?

13 μμF

A given capacitor stores 13 μμC of charge for every volt applied across the plates. What is its capacitance?

5.41 x 1014 Hz

A light wave has a wavelength of 555 x 10−−9 m. What is its frequency?

−− 0.11 D

A nearsighted individual has a near point of 9.1 m. What refractive power corrective contact lens will be required to give them normal vision?

4.6 m

A person aims a laser pointer at a mirrored wall as shown. Given the dimensions shown, at what value of y above the floor will the laser spot appear on the wall behind the person?

virtual

A plane mirror produces an image that is:

out of the page

A positive charge is traveling upward in the plane of the page (toward the top of the page). A magnetic field in the region points leftward in the plane of the page. In which direction will the magnetic force on the moving charge point?

1400 N/C

A positive particle enters the region of electric and magnetic fields as shown below (same as the previous question). If this is to be used as a velocity selector, and the magnetic field strength is 0.35 T, what is the strength of the electric field required to allow particles with a speed of 4.0 x 103 m/s to pass through the region at constant velocity?

2.6 x 10−−7 kg/C

A positive particle enters the region of electric and magnetic fields as shown below. This is to be used as a velocity selector with a magnetic field strength of 0.35 T, and particles with a speed of 4.0 x 103 m/s will pass through at constant velocity (everything is the same as in the previous question). After passing through the region where both fields are present, the electric field now ceases to exist, but the magnetic field continues. In the region with just the magnetic filed, the radius of the particle's curved path is 3.0 mm. What is the ratio of mass to charge on this particle? (find mqmq )

it will bend away from the normal by a lesser amount

A ray of white light in glass arrives at a surface between the glass and air on the other side. If the blue light bends away from the normal as it refracts through the surface, what will happen to the red light?

yes

A rectangular loop of wire in the plane of the page carries a clockwise current as shown below. The loop is free to possibly rotate about the rotation axis shown. With a magnetic field pointing to the right, would the current loop begin to rotate about this axis? (Hint: think about the forces acting on each segment of wire.)

290 V

A rotating generator has N = 170 windings that enclose an area A = 0.050 m2. If the generator rotates at a speed ωω = 31 rad/s in a magnetic field B = 1.1 T, what will be the maximum induced emf in the generator?

3.75 x 10−−3 T⋅⋅m2

A single rectangular loop of wire with a width of .0500 m and a height of .0300 m lies in the plane of the page. If a uniform magnetic filed of 2.50 T points out of the page in this region, what is the magnetic flux through the rectangular loop?

A

An object is placed 55 cm in front of a convex (diverging) mirror with a focal length of −−25 cm as shown in the first picture. Which of the options shown in the second picture is the P-ray?

the amount of charge that can be stored on a capacitor per volt applied across the capacitor

Capacitance is an indication of:

It's not necessarily a disaster, but it can lead to further confusion and it's best to understand the difference

Electric force and electric field are two different but closely related things that are easy to get confused with each other. If you ever think or say force when you should be thinking field, (or vice-versa):

88%

For a charging RC circuit (with the capacitor initially uncharged), what percentage of full charge will the capacitor have at t = 2.1 ττ after the switch is closed?

using light that is closer to the red end of the spectrum

For double-slit interference, which of the following will cause the spread of the pattern on the screen to be greater?

−−17 cm

For the convex mirror situation described above (do = 55 cm, f = −−25 cm), what will be the image distance di?

B, then A and C tie

For the diagram above , rank the charges in order of increasing magnitude of the net force they experience, indicating ties where appropriate (look carefully, the diagram is different than one you may have seen in the practice problems).

3.8 x 10−−4 J

For the same situation as in question 1, if 9.0 V is applied across A and B, how much energy is stored on the equivalent capacitor?

84 μμC and 84 μμC

For the same situation as in question 1, if 9.0 V is applied across A and B, what is the charge on C1 and C2 respectively?

9.0 V and 9.0 V

For the same situation as in question 4, if 9.0 V is applied across A and B, what is the voltage on C1 and C2 respectively?

8.5 x 10−−5 C

For the same situation as in question 6, if 9.0 V is applied across A and B, what is the charge on C1?

1.08 x 10−−5 N

For the situation above, if the charge is +6.00 x 10−−9 C travelling at 1200 m/s and the magnetic field has a magnitude of 1.5 T, what is the magnitude of the magnetic force?

counterclockwise

For the slide wire generator shown in the diagram below, if the bar is moving to the right and the magnetic filed points into the page, in which direction (clockwise or counter clockwise) is the induced current in the loop?

the second equation is the definition of electric filed, and the third one is the typical way of calculating electric field due to a point charge

For the snippet of your equation sheet shown below, which of the following statements is true?

1.25 x 10^13

How many electrons are missing from an object that has a net charge of +2.00 x 10^-6 coulombs?

0.075 W

How much power is dissipated in a copper wire (ρρ = 1.68 x 10−−8 ΩΩ⋅⋅m) with a radius of 1.00 mm and a length of 1.0 cm when 2.0 x 10−−3 volts is applied across the ends?

False

If only a single point charge is present in a region of space, it wouldn't make any sense to talk about potential (voltage) in that region.

the image is inverted and the mirror is concave

If the magnification of an image created by a mirror is negative, which of the following is correct?

it will double

If the speed of the particle described in question 2 is doubled, what will happen to the magnitude of the magnetic force?

9.4 x 10−−4 V

If, in the situation described in question 4 above, the magnetic field increases steadily to 5.0 T over a span of 4.0 seconds (while pointing out of the page the whole time), what will be the induced emf in the rectangular coil during this time?

zero

If, in the situation described in question 4 above, the magnetic field stays constant at 2.5 T, but the rectangular loop rotates over a span of 4.0 seconds while staying in the plane of the page, so that its width becomes .0300 m and its height becomes 0.0500 m (in other words it rotates so that its long dimension becomes vertical instead of horizontal) , what will be the induced emf in the rectangular coil during this time?

the force will be zero

In a different situation, everything is the same as in question 1, except that the particle is traveling to the left in the plane of the page instead of upward. What is the direction of the magnetic force on the particle in this new situation?

53∘

In a double-slit experiment, blue light (λλ = 400 nm) is shown through a pair of slits that are separated by 1.00 μμm. What will be the angle from the central axis to a 2nd order bright fringe?

545 μμm

In a double-slit experiment, what wavelength of light, when shown through a pair of slits that are separated by 1.00 μμm, will have a 1st order bright fringe at 33∘∘?

Both situations have equal potential energies

In situation A, two positive charges of +1.0 C each are located on the y-axis, with one charge at the origin and one at y = 1.0 m. In situation B, two negative charges of −−1.0 C each are located on the x-axis, with one charge at the origin and one at x = 1.0 m. Which situation has a higher potential energy (relative to U = 0 with all charges infinitely far apart)?

0.41 A

In the RC circuit shown below, the battery emf is 9.0 V, R1 = 11 ΩΩ, R2 = 22 ΩΩ, and the capacitor is initially uncharged. What is the current from the battery a long time after the switch is closed?

40 μμF

In the diagram below, C1 = 15 μμF and C2 = 25 μμ F. What is the equivalent capacitance of these two capacitors?

9.4 μμF

In the diagram below, C1 = 15 μμF and C2 = 25 μμF (μμ means 10−−6). What is the equivalent capacitance of these two capacitors?

9.5 μμF

In the diagram below, C1 = 15 μμF, C2 = 25 μμF, C3 = 35 μμF, and C4 = 45 μμF. What is the equivalent capacitance of this network of capacitors?

0.026 T m2

In the diagram below, the arrow pointing to the right represents a magnetic field with a magnitude of 3.7 T. The thicker line at an angle represents the side view of a single loop of wire with a radius of 5.1 cm, and the dashed line represents the normal to the loop. What is the magnetic flux through this loop? (The area of a circle is ππr2)

No

In the situation shown in any of the previous questions, do any light rays ever travel behind the mirror?

the equipotentials will always be perpendicular to the electric field lines

On an electric field map that shows electric field lines and lines of equal potential:

the charge on the left is negative and the charge on the right is positive

The blue lines in the figure below represent electric field. Which of the following statements is true?

A and D would be the same; B and C would be the same

The diagrams below show four separate cases where a bar magnet is moved toward or away from a loop of wire. In which of the cases would the direction of the induced emf in the loop be the same? (Hint: you don't need to figure out the direction for each one, just think about how the flux is changing in each case.)

no limit

The far point for normal human vision is:

to form a virtual image at a location where the person's eye can focus on it

The goal of corrective optics for human nearsightedness and farsightedness is:

real, inverted, and enlarged

The image formed by a concave mirror when the object is placed between the focal point and the center of curvature has the following characteristics:

is always the same distance behind the mirror as the object is in front of the mirror

The image formed by a plane mirror:

virtual, upright, and reduced

The image produced in the convex mirror situation described above (do = 55 cm, f = −−25 cm) will be:

25 cm

The near point for normal human vision is:

False

The near point of a "normal" human eye is infinity.

1 T⋅⋅m2

The official SI unit for magnetic flux is the weber (Wb). 1 Wb is equivalent to:

dispersion

The phenomenon of different wavelengths of light bending by slightly different amounts when passing between the same two transparent materials (and with the same angle of incidence) is referred to as:

constructive

The two sources of radio waves shown below emit identical, coherent signals. The concentric circles represent wave crests of the two signals. At the point marked P, the interference is:

True

True/False: Diffraction gratings are often used for accurately determining the wavelength of a light source.

True

True/False: In the situation described in question 1 above, the direction of the induced emf will depend on things like which pole of the magnet is facing the coil, and in which direction you move the magnet relative to the coil.

1.86 N

Two point charges (Q1 = 2.57 x 10^-6 C and Q2 = -8.24 x 10^-6 C) are separated by a distance of 32.0 cm. What is the magnitude of the force that they exert on each other?

1.4 x 108 N/C

Two point charges (q1 = 6.2 x 106 C and q2 = 3.7 x 10 6 C) are placed at the origin (q1) , and at (x=2.0 cm, y = 2.0cm) (q2). What is the magnitude of the electric field contribution just from q1 at the position (x = 2.0 cm, y =0)?

up and to the right

Two point charges (q1 = 6.2 x 10−−6 C and q2 = −− 3.7 x 10−− 6 C) are placed at the origin (q1) , and at x=2.0 cm, y = 2.0cm (q2). In which direction would you expect the net electric field at the position (x = 2.0 cm, y = 0) to point? (in the plane of the page)

−−7.3 J

Two point charges (q1 = 6.2 x 10−−6 C and q2 = −− 3.7 x 10−− 6 C) are placed at the origin (q1) , and at x=2.0 cm, y = 2.0cm (q2). What is the electric potential energy of this system?

3.9 x 10^6 N/C

What is the magnitude of the electric field at a distance of 16 cm from a charge of −11μ−11μC?

two wave troughs arrive at the same place simultaneously

Which of the following are situations in which constructive interference would occur?

green

Which of the following colors of light has the shortest wavelength?

The magnetic force depends on a charged particle's speed, the electric force does not

Which of the following is a correct statement about the difference between the electric force and the magnetic force ?

Electric field is a vector, and the direction matters (except sometimes when you are only asked about a magnitude)

Which of the following statements about electric field is true?

increase the gap distance d

Which of the following would decrease the capacitance of a parallel plate capacitor?

A = D < B < C

You are using a bar magnet and a coil of wire to generate an emf (voltage) in the coil. Rank the following scenarios in order of increasing emf generated: A) holding a relatively strong magnet motionless near the coil B) holding a relatively weak magnet relatively far from the coil and moving it quickly C) holding a relatively weak magnet near the coil and moving it quickly D) holding a relatively weak magnet motionless near the coil