Summer 2000 Physics 102 Hour Exam 2(20 questions)

The grading button and a description of the scoring criteria are at the bottom of this page. Basic questions are marked by a single star *. More difficult questions are marked by two stars **. The most challenging questions are marked by three stars ***

This exam consists of 20 questions; two-choice questions are worth 2 points each, three-choice questions are worth 3 points each, five-choice questions are worth 6 points each. The maximum possible score is 83. When the exam was given, the minimum "A" score was 74; the minimum "B" was 64; the minimum "C" was 54; the minimum "D" was 42. The mean was 68.4; the median was 70. Click here to see formula sheet 1, formula sheet 2 that came with the exam.

QUESTION 1*

This and the next three questions pertain to the following situation:

The drawing shows the top view of four interconnected chambers. Each chamber has a unique magnetic field. A positively charged particle is fired into chamber 1, and observed to follow the dashed path shown in the figure.

The direction of the magnetic field in chamber 1 is out of the page.

(T)   True
(F)   False

QUESTION 2*

The direction of the magnetic field in chamber 4 is out of the page.

(T)   True
(F)   False

QUESTION 3*

The magnitude of the magnetic field in chamber 3 is greater than the magnitude of the field in chamber 4.

(T)   True
(F)   False

QUESTION 4**

The speed of the particle in chamber 1 is greater than the speed of the particle in chamber 2.

(T)   True
(F)   False

QUESTION 5*

This and the next two questions pertain to the following situation:

The Particle Spectrometer shown here consists of a uniform magnetic field |B| = 1.25 T either into or out of the page, in the region of the shaded box. Particles #1 through #3 all have charge magnitude |q| = 1.6 × 10-19 C. They enter with the same initial velocity v = 6 × 105 m/s and follow the trajectories shown.

Which particle is most massive?

(a)   #1
(b)   #2
(c)   #3

QUESTION 6*

The mass of particle #3 is determined to be 1.67 × 10-27 kg. Calculate the distance L labeled on the diagram.

(a)   L = 2.5 × 10-3 m
(b)   L = 5.0 × 10-3 m
(c)   L = 6.0 × 10-3 m
(d)   L = 7.5 × 10-3 m
(e)   L = 10.0 × 10-3 m

QUESTION 7*

What is the magnitude of the force on particle #3 when it is at the point marked a (the top of its trajectory)?

(a)   F = 1.5 × 10-14 N
(b)   F = 3.0 × 10-14 N
(c)   F = 6.0 × 10-14 N
(d)   F = 1.2 × 10-13 N
(e)   F = 2.4 × 10-13 N

QUESTION 8*

This and the next two questions pertain to the following situation:

Two fixed conductors are connected by a resistor of resistance 12 ohms. The two fixed conductors are separated by 2.25 m. A moving conductor slides on them at velocity 5 m/s. Out of the page is a uniform magnetic field (shown by the black dots in the figure) with a magnitude of 3.33 × 10-3 T. Points a and b are two points on the circuit at the ends of the resistor.

In which direction does the current flow through the resistor?

(a)   from a to b
(b)   from b to a

QUESTION 9*

What force must be applied to the bar to keep it moving at constant velocity?

(a)   1.17 × 10-5 N
(b)   2.34 × 10-5 N
(c)   4.51 × 10-5 N
(d)   6.00 × 10-5 N
(e)   1.51 × 10-4 N

QUESTION 10*

What is the power being dissipated by the resistor?

(a)   1.2 × 10-5 W
(b)   6.8 × 10-5 W
(c)   3.7 × 10-5 W
(d)   11.7 × 10-5 W
(e)   73.2 × 10-5 W

QUESTION 11*

This and the next two questions pertain to the following situation:

In this problem all voltages and currents given and asked for are rms values. The values of the frequency of the generator, the capacitance, inductance, and impedance of the circuit are given to the right of the circuit, along with the rms current flowing in the circuit.

What is the resistance R of this circuit?

(a)   R = 228 W
(b)   R = 242 W
(c)   R = 333 W
(d)   R = 404 W
(e)   R = 427 W

QUESTION 12*

What is the rms voltage of the generator?

(a)   42.0 V
(b)   50.8 V
(c)   69.9 V

QUESTION 13*

Calculate VC, the rms voltage across the capacitor.

(a)   VC = 0.0 V
(b)   VC = 11.6 V
(c)   VC = 24.5 V
(d)   VC = 41.8 V
(e)   VC = 50.8 V

QUESTION 14*

This and the next three questions pertain to the following situation:

A wire loop with a current I = 5 A flowing in the direction shown is in a uniform magnetic field of strength B = 0.002 T. The initial orientation of the loop is flat on the page and the field runs from top to bottom, in the plane of the page, as shown.

What is | Fab | the magnitude of the magnetic force on side ab?

(a)   | Fab | = 0 N
(b)   | Fab | = 1.0 × 10-3 N
(c)   | Fab | = 5.0 × 10-3 N
(d)   | Fab | = 1.0 × 10-2 N
(e)   | Fab | = 5.0 × 10-2 N

QUESTION 15*

The direction of the force on side ab is

(a)   out of the page.
(b)   into the page.

QUESTION 16*

The magnitude of the torque on the loop is

(a)   0 Nm
(b)   1.0 × 10-3 Nm
(c)   5.0 × 10-3 Nm

QUESTION 17*

If the magnetic field were oriented from left to right instead of from top to bottom, the loop would not feel a torque.

(T)   True
(F)   False

QUESTION 18**

This and the next two questions pertain to the following situation:

The wires are located at (-3,0) meters and (3,0) meters. They both carry 4A coming out from the sheet of the paper.

What is By, the y component of the magnetic field at the origin?

(a)   By = -9 × 10-7 T
(b)   By = -4.5 × 10-7 T
(c)   By = 0 T
(d)   By = +4.5 × 10-7 T
(e)   By = +9 × 10-7 T

QUESTION 19***

What is the x-component of the force on a 5 meter long segment of wire B due to the magnetic field from wire A?

(a)   F= -2.67 × 10-6 N
(b)   F= -1.33 × 10-6 N
(c)   F= 0 N
(d)   F= +1.33 × 10-6 N
(e)   F= +2.67 × 10-6 N

QUESTION 20**

Now a third wire C, carrying 2A coming out of the page is placed at location (-3,3) meters.

Which arrow above best represents the direction of the force on C due to the currents in wires A and B?

(a)
(b)
(c)
(d)
(e)

Scoring of True-False (T,F) Questions:
• If you mark the correct answer, you get 2 points.
• If you mark the wrong answer or if you mark neither answer, you get 0 points.
Scoring of Multiple Choice I (a,b,c) Questions:
• If you mark the correct answer, you get 3 points.
• If you mark a wrong answer or if you mark none of the answers, you get 0 points.
Scoring of Multiple Choice II (a,b,c,d,e) Questions:
• If you mark one answer and it is the correct answer, you get 6 points.
• If you mark two answers and one of them is the correct answer, you get 3 points.
• If you mark three answers and one of them is the correct answer, you get 2 points.
• If you do not mark the correct answer, or if you mark more than three answers, or if you mark none of the answers, you get 0 points.