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 150. The exam period was 90 minutes; the mean score was 116.4 the median was 118. 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 resistor and a battery.

What happens to the current in the resistor when the voltage is doubled and the resistance remains the same?

(a) It is doubled. (b) It is quadrupled. (c) It is halved. (d) It is quartered. (e) It remains the same.

I) the material from which it is made II) the length of the resistor III) the diameter of the resistor

(a) R_{B} / R_{A} = 4/9 (b) R_{B} / R_{A} = 2/3 (c) R_{B} / R_{A} = 1 (d) R_{B} / R_{A} = 3/2 (e) R_{B} / R_{A} = 9/4

(a) 2 J (b) 10 J (c) 20 J (d) 100 J (e) 200 J

(a) C_{B} / C_{A} = 1/4 (b) C_{B} / C_{A} = 1/2 (c) C_{B} / C_{A} = 1 (d) C_{B} / C_{A} = 2 (e) C_{B} / C_{A} = 4

(a) The potential difference decreases and the stored energy increases. (b) Both the potential difference and the stored energy increase. (c) The potential difference increases and the stored energy decreases. (d) Both the potential difference and the stored energy decrease. (e) Both the potential difference and the stored energy remain the same.

In the circuit shown below, the battery voltage is 9 V, the resistor R_{1} = 20 Ω and the capacitor C = 1 μF. The capacitor is initially charged with the polarity shown in the picture and with a voltage of 18 V. Switches S_{1} and S_{2} are initially open.

What is the initial charge on the capacitor?

(a) 11 C (b) 1.8 × 10^{-5} C (c) 3.2 × 10^{-3} C (d) 1.5 × 10^{-5} C (e) 4.1 × 10^{-9} C

(a) 0.2 A (b) 0.9 A (c) 1.0 A (d) 0.5 A (e) 0.3 A

(a) 2.0 × 10^{-5} s (b) 1.0 s (c) 3.2 × 10^{-6} s (d) 5.4 × 10^{-9} s (e) 10 s

(a) 2.0 A (b) 0.23 A (c) 0.45 A (d) 20 A (e) 0.15 A

In the circuit shown below, the battery voltage is ε, the resistors R_{1} = R_{3} = R and R_{2} = R_{4} = 2R.

What is the equivalent resistance for this configuration of resistors?

(a) 5R (b) R / 10 (c) 3R / 2 (d) 6R / 5 (e) R

(a) ε^{2} / 10R (b) ε^{2} / R (c) ε^{2} / 5R (d) ε^{2} / 20R (e) ε^{2} / 3R

(a) 3 Ω (b) 1 Ω (c) 10 Ω (d) 2 Ω (e) 0.1 Ω

(a) V_{AB} > 0 (b) V_{AB} < 0 (c) V_{AB} = 0

In a cathode ray tube (CRT), a beam of electrons is deflected vertically by a constant electric field between parallel plates of length L = 2 cm, separated a distance d = 1 cm. The electrons (charge q = -1.6 ×10^{-19} C, and mass m_{e} = 9.11 × 10^{-31} kg), travel at a velocity v = 3 × 10^{6}m/s along the horizontal. You may neglect the effect of gravity on the electrons.

What is the horizontal velocity component of the electrons after passing through the parallel plates?

(a) 1 × 10^{6} m/s (b) 3 × 10^{6} m/s (c) 5 × 10^{6} m/s (d) 7 × 10^{6} m/s (e) 9 × 10^{6} m/s

(a) The beam would deflect the same amount, in the opposite direction. (b) The beam would deflect more, in the opposite direction. (c) The beam would deflect more, in the same direction. (d) The beam would deflect less, in the opposite direction. (e) The beam would deflect less, in the same direction.

A hollow, conducting cylinder is placed between two long, oppositely charged parallel plates. Consider the following diagrams.

Which diagram best represents the equipotential lines for this situation?

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

(a) toward the positive electrode (b) toward the negative electrode (c) It does not move.

A neuron can be modeled as a parallel plate capacitor, with the membrane acting as a dielectric and ions as charges on the plates. The membrane has a dielectric constant κ = 7.0 and a thickness of d = 6.0 nm.

In its resting state, the inside of the cell is at a potential of -85 mV relative to the outside.

What is the capacitance of a 1 (μm)^{2}, (10^{-12} m^{2}), area of membrane?

(a) 0.0015^{ }pF (b) 0.01 pF (c) 0.3 pF (d) 4.7 pF (e) 7.5 pF

(a) into the cell (b) out of the cell

(a) 3.7 × 10^{2} (b) 1.3 × 10^{3} (c) 5.4 × 10^{3} (d) 9.1 × 10^{3} (e) 1.2 × 10^{5}

A single charge of unknown sign and magnitude is located at the origin. A graph of the electrical potential a distance r away from this charge is shown below. We assume that the potential at infinity is zero. The graph is accurately prepared so you can read meaningful values from scales on the axes.

The sign of the charge is

(a) positive (b) negative

(a) |Q| = 0.22 nC (b) |Q| = 5.55 nC (c) |Q| = 50.0 nC

(a) W = 0.15 μJ (b) W = 0.80 μJ (c) W = 1.33 μJ (d) W = 8.66 μJ (e) W = 25.0 μJ

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

What is the sign on the charge Q_{1}?

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

(a) W = -4 μJ (b) W = -2 μJ (c) W = 0 μJ (d) W = 2 μJ (e) W = 4 μJ