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 125. The exam period was 90 minutes; the mean score was 79.2 the median was 79. Click here to see page1 page2 page3 of the formula sheet that came with the exam.

Some helpful information: • 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 consists of a 6 V battery, 3 resistors and 2 capacitors as depicted below. Both capacitors are initially uncharged. Switch S_{1} is then closed at time t = 0. Switch S_{2} remains open until stated otherwise.

What is the voltage V_{1} across C_{1} right when S_{1} is closed (at t = 0)?

(a) V_{1} = 0 V (b) V_{1} = 2 V (c) V_{1} = 4 V

(a) P = 0 W (b) P = 0.12 W (c) P = 0.24 W (d) P = 0.72 W (e) P = 1.2 W

(a) I_{3} = 0 A (b) I_{3} = 0.3 A (c) I_{3} = 0.6 A (d) I_{3} = 0.8 A (e) I_{3} = 1.6 A

(a) C_{2} = 2 μF (b) C_{2} = 3 μF (c) C_{2} = 4 μF (d) C_{2} = 6 μF (e) C_{2} = 12 μF

What is the equivalent resistance R_{eq} of the circuit?

(a) R_{eq} = 5R/6 (b) R_{eq} = 7R/6 (c) R_{eq} = 6R/5 (d) R_{eq} = 36R/13 (e) R_{eq} = 5R

(a) ΔV = 4 V (b) ΔV = 4.8 V (c) ΔV = 8 V

A circuit consists of a battery, a capacitor and two resistors in the configuration shown below. Initially, the switch is open and the capacitor is uncharged. The values associated with the parameters of the circuit are ε = 12 V, C = 3 μF, R_{1} = 22 Ω and R_{2} = 15 Ω.

The switch is closed and the capacitor is allowed to charge. When the charge on the capacitor reaches 10 μC, what is the current I_{1} through R_{1}?

(a) I_{1} = 0.00 A (b) I_{1} = 0.15 A (c) I_{1} = 0.22 A (d) I_{1} = 0.32 A (e) I_{1} = 0.39 A

(a) I_{2} = 0.023 A (b) I_{2 }= 0.32 A (c) I_{2} = 1.20 A (d) I_{2} = 1.67 A (e) I_{2} = 3.10 A

You are given a circuit consisting of five capacitors and a battery, as shown.

What is the total equivalent capacitance C_{eq} of the circuit?

(a) C_{eq} = 1.7 μF (b) C_{eq} = 7.6 μF (c) C_{eq} = 12.8 μF

(a) Q_{3} = 12.7 μC (b) Q_{3} = 18.3 μC (c) Q_{3} = 27.5 μC (d) Q_{3} = 31.8 μC (e) Q_{3} = 45.8 μC

Four charges are placed at the corners of a rectangle with sides of length 3 cm and 4 cm as shown below.

What is the direction of the electric field at the center of the rectangle due to these charges?

(a) in the +x direction (b) in the +y direction (c) in the -y direction

(a) |E| = 2.56 × 10^{5} N/C (b) |E| = 34.6 × 10^{6} N/C (c) |E| = 1.38 × 10^{8} N/C (d) |E| = 2.93 × 10^{9} N/C (e) |E| = 16.5 × 10^{9} N/C

(a) W_{total} = 0 J (b) W_{total} = 10 J (c) W_{total} = 30 J (d) W_{total} = 45.5 J (e) W_{total} = 125 J

(a) W_{field} = 3.20 × 10^{-19} J (b) W_{field} = 0.75 × 10^{-19} J (c) W_{field} = 0 J (d) W_{field} = -3.88 × 10^{-17} J (e) W_{field} = -5.23 × 10^{-17} J

(a) Yes (b) No

(a) C_{eq} = 4 C_{0} (b) C_{eq} = 4 C_{0} / 3 (c) C_{eq} = 3 C_{0} / 4 (d) C_{eq} = C_{0} / 4 (e) none of the above

A fixed, conducting sphere A has a net positive charge. A second conducting sphere B that hangs from the ceiling is placed to the right of the fixed sphere A, as shown in the figure. Sphere B has NO net charge. Assume the spheres are ideal conductors.

The electric force between spheres A and B is

(a) repulsive. (b) attractive. (c) zero.

This is a map of equipotential lines for two charges Q_{1} and Q_{2}. Potential values are accurate and given in volts.

Which one of the following statements about the magnitudes of the charges is true?

(a) |Q_{1}| > |Q_{2}| (b) |Q_{1}| = |Q_{2}| (c) |Q_{1}| < |Q_{2}|

(a) up (b) down (c) right (d) left (e) pointing towards charge Q_{2}

(a) ΔU = -2 μJ (b) ΔU = 0 μJ (c) ΔU = 2 μJ

A capacitor is composed of two parallel plates of area 5 × 10^{- 4}m^{2} separated by a distance 7 × 10^{-4}m as shown below.

Consider the situation when the capacitor is in isolation and charged to maximum capacity. The electric field in this situation is 2 × 10^{6} V/m.

What is the charge Q on one of the plates of the capacitor?

(a) Q = 6.89 × 10^{-12} C (b) Q = 8.85 × 10^{-9} C (c) Q = 4.67 × 10^{-6} C

(a) accelerates to the right at 0.0025 m/s^{2}. (b) accelerates to the left at 0.382 m/s^{2}. (c) remains motionless since it is the equilibrium point.

Now consider a slab of dielectric constant κ = 3.2 inserted in between the plates as shown in situation B above. Compared to the situation having no dielectric present, how do i) the voltage V across the plates and ii) the stored potential energy U change?

(a) Both V and U increase. (b) V increases and U decreases. (c) V decreases and U increases. (d) Both V and U decrease. (e) Both stay the same.

(a) t_{5} = 2.87 × 10^{-12} s (b) t_{5} = 1.02 × 10^{-8} s (c) t_{5} = 3.51 × 10^{-4} s (d) t_{5} = 1.32 s (e) t_{5} = 6.44 × 10^{4} s

Four resistors and two batteries are connected as shown below. The corresponding resistances and voltages have the values R_{1 } = R_{2} = R_{3} = R_{4 } = 2 Ω and ε_{1} = ε_{4}= 4 V. Define currents I using the directions given by the arrows.

When the switch S is in the 'open' position (as shown), what is the value of the current I_{23}?

(a) I_{23 }= 0.5 A (b) I_{23 }= 1.33 A (c) I_{23 }= 6.75 A

(a) ε_{1} - I_{1}R_{1} + I_{2}R_{2} = 0 (b) I_{1} + I_{23} - I_{4} = 0 (c) ε_{1} - I_{1}R_{1} + I_{4}R_{4} - ε_{4} = 0