True-false questions are worth 2 points each, three-choice multiple choice questions are worth 3 points each, five-choice multiple choice questions are worth 6 points each. The maximum possible score is 100. The exam period was 90 minutes; the mean score was 60.2 the median was 61. Click here to see the formula sheet that came with the exam.

Some helpful information: • A physics 102 light bulb acts just like a resistor: its resistance is constant, independent of the current flowing through the light bulb. The bulb's brightness increases with increasing current. • A reminder about prefixes: p (pico) = 10^{-12}; n (nano) = 10^{-9}; μ (micro) = 10^{-6}; m (milli) = 10^{-3}; k (kilo) = 10^{+3}; M or Meg (mega) = 10^{+6}; G or Gig (giga) = 10^{+9}.

A circuit is built out of three dissimilar light bulbs and two batteries as shown in the following diagram. The point labeled "ground" at the lower left corner of the circuit is at zero volts.

According to Kirchoff's Current Rule:

(a) I_{1} = I_{2} = I_{3} (b) I_{1} + I_{2} = I_{3}

(a) 1.5 A (b) 1.0 A (c) 6.0 A

(a) 0.9 V (b) 6.0 V (c) 7.2 V

(a) 0.9 A (b) 0.67 A (c) 4.5 A (d) -1.5 A (e) -0.6 A

Which of the following graphs best represents the voltage across the capacitor V_{C}?

(a) (b) (c)

The current that flows in the circuit 0.2 seconds after the switch is closed is

(a) 2.67 mA (b) 4.0 μA (c) 0.33 mA

(a) 4 V (b) 8 V (c) 6 V

(T) True (F) False

Consider a capacitor made from two large, parallel conducting planes. The left plane has a positive charge, and the right plane has an equal amount of negative charge.

Compare the magnitudes of the electric fields E_{A}, E_{B}, and E_{C} at positions A, B, and C, respectively. Which one of the following statements is correct?

(a) E_{A} > E_{B} > E_{C} (b) E_{A} < E_{B} < E_{C} (c) E_{A} = E_{B} = E_{C} (d) E_{A} = E_{C} > E_{B} (e) E_{A} = E_{C} < E_{B}

(a) W_{BA} = W_{BC} (b) W_{BA} > W_{BC} (c) W_{BA} < W_{BC}

A hollow, conducting cylinder is placed in front of a long, conducting plane. The cylinder is negatively charged, while the plane has an equal amount of positive charge. Consider the following diagrams. Only one diagram is correct.

Which diagram best represents the equipotential lines for this situation?

(a) A (b) B (c) C (d) D (e) There is insufficient information to answer.

(a) A negative point charge placed at the center of the cylinder will experience a force to the left, toward the positive electrode. (b) The electric field lines inside the cylinder point radially inward, toward the center. (c) The electric potential energy is everywhere constant inside the cylinder.

Calculate the magnitude and direction of the net force on object "B" due to the charges on object "A".

(a) 8.125 × 10^{-4} N, pointing left. (b) 8.125 × 10^{-4} N, pointing right. (c) 9.812 × 10^{-3} N, pointing left. (d) 9.812 × 10^{-3} N, pointing right. (e) The force is zero.

A neutral conducting cylinder is placed an equal distance from two charged conducting planes and is free to move in any direction. The left plane is positively charged, and the right plane is negatively charged. The left plane has twice the amount of charge as the right plane. Does the cylinder move, and, if so, in what direction?

(a) The cylinder moves toward the positively charged plane. (b) The cylinder moves toward the negatively charged plane. (c) The cylinder does not move.

Three charges are fixed at positions (3,4), (0,0), and (6,0) as shown in the figure: q_{A} = +2 µC, q_{B} = -1 µC and q_{C} = +1 µC. The grid spacing is one meter.

Calculate the magnitude of the force on charge A due to the charges B and C.

(a) 1.152 × 10^{-3} N (b) 4.320 × 10^{-4} N (c) 8.640 × 10^{-4} N

(a) W_{A} = 0 J, W_{B} = +1.5 × 10^{-3} J, W_{C} = 0 J (b) W_{A} = 0 J, W_{B} = -1.5 × 10^{-3} J, W_{C} = 0 J (c) W_{A} = -3.6 × 10^{-3} J, W_{B} = +1.5 × 10^{-3} J, W_{C} = 0 J (d) W_{A} = -3.6 × 10^{-3} J, W_{B} = +1.5 × 10^{-3} J, W_{C} = +3.6 × 10^{-3} J (e) W_{A} = +3.6 × 10^{-3} J, W_{B} = -1.5 × 10^{-3} J, W_{C} = -3.6 × 10^{-3} J

Through which resistor flows the smallest current?

(a) 5 Ω resistor (b) 2 Ω resistor (c) 3 Ω resistor

(a) 10.0 Ω (b) 6.2 Ω (c) 8.7 Ω

(a) The power would increase by a factor of two. (b) The power would decrease by a factor of two. (c) The power would not change. (d) The power would decrease by a factor of four. (e) The power would increase by a factor of four.

The copper wire is a cylinder with diameter 1 mm and length 25 mm. The resistivity of copper is ρ = 1.72 × 10^{-8} Ω-m. What is the resistance of the wire measured along its 25 mm length?

(a) 0.55 mΩ (b) 1.2 Ω (c) 25 Ω

(a) The resistance does not change. (b) The resistance increases by a factor four. (c) The resistance increases by a factor two.

Two metallic parallel plates of identical square shape with side length L = 1 cm are separated by an air gap d of 0.2 cm. The charge on the capacitor is Q = + 2 nC.

What is the electric potential difference between the two plates?

(a) 4.5 × 10^{3} volts (b) 1.3 volts (c) 0.02 volts

(a) The energy will double. (b) The energy will not change. (c) The energy will be halved.

All three capacitors are identical and have capacitances of 2 μF. A 9 V battery is connected as illustrated. The circuit was assembled in the distant past.

What is the equivalent capacitance of the network connected to the battery?

(a) 3 μF (b) 1.5 μF (c) 6 μF

(a) The charge on C_{1} is double the charge on C_{2}. (b) There is no current flowing through C_{1}. (c) The energy stored in C_{1} is twice the energy stored in C_{2}. (d) Voltage drops across C_{2} and C_{3} are identical. (e) C_{2} and C_{3} have the same amount of charge.

(a) Q_{3} will stay the same. (b) Q_{3} will increase. (c) Q_{3} will decrease.