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 89. The exam period was 75 minutes; the mean score was 53.0 the median was 52. Click here to see page1 page2 page3 of 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}.

This apparatus consists of two conducting spheres resting on insulated supports, connected by a narrow conducting rod. You should assume that the apparatus is electrically neutral. Bring a negatively-charged rubber rod close to (but not touching) the sphere on the left.

Consider the electrical force, if any, exerted by the rod on the pair of spheres. What can we say about that force? (Ignore all forces other than that electrical force.)?

(a) The rod repels the apparatus to the right. (b) The rod exerts no overall electrical force on the system. (c) The rod attracts the apparatus to the left.

(a) The sphere on the left is positively charged; the sphere on the right is negatively charged. (b) The spheres are both neutral. (c) The sphere on the right is positively charged; the sphere on the left is negatively charged.

(a) collapse (move closer) because the total voltage of the system increases. (b) collapse (move closer) because charge moves onto the plates of the capacitor. (c) spread farther apart because charge is pushed off the plates of the capacitor.

A pair of charges sits on the x-axis: a charge q = -6 nC at the origin and q = +8 nC at x = 4. Assume no other charges are present.

What is the (electrical) stored energy of this pair of charges?

(a) - 1.08 × 10^{-7} J (b) - 2.7 × 10^{-8} J (c) 0 (d) + 2.7 × 10^{-8} J (e) + 1.08 × 10^{-7} J

(a) x = 1.71 (b) x = 1.86 (c) There is no such point.

(a) x = 1.71 (b) x = 1.86 (c) The electric potential is not equal to zero at either of the points listed above.

A negative charge q = -7 nC is fixed at the origin. A positive charge q = + 7nC is fixed on the y-axis at y = 6. For the sake of reference, consider point A, at (x = 5, y = 3). All distances quoted are in meters.

In what direction does the electric field at A point?

(a) There is no electric field at A. (b) The field at A points rightward along the page (positive x direction). (c) The field at A points leftward along the page (negative x direction). (d) The field at A points upward along the page (positive y direction). (e) The field at A points downward along the page (negative y direction).

(a) 0 N (b) 1.48 × 10^{-8} N (c) 1.53 × 10^{-8} N (d) 2.96 × 10^{-8} N (e) 3.05 × 10^{-8} N

(a) It will depend on the path taken: W < 0 if the particle is brought to A from the upper half of the plane, and positive otherwise. (b) It will depend on the path taken: W > 0 if the particle is brought to A from the upper half of the plane, and negative otherwise. (c) W = 0

Consider this circuit. (Points A and B in the circuit are labeled for the sake of reference.)

What is the charge on the 6 μF capacitor?

(a) 144 μC (b) 180 μC (c) 216 μC (d) 288 μC (e) 312 μC

(a) 144 μJ (b) 180 μJ (c) 216 μJ (d) 288 μJ (e) 312 μJ

(a) It has no effect. (b) It increases the difference V_{A} - V_{B}. (c) It decreases the difference V_{A} - V_{B}.

Six identical resistors are connected as shown. Various batteries may be attached to that resistor network. For the sake of reference, points A, B, and C, and current I, are identified.

Find the single resistance equivalent to the original network of six resistors.

(a) 10.9 Ω (b) 45 Ω (c) 55 Ω (d) 60 Ω (e) 120 Ω

(a) 0.167 A (b) 0.5 A (c) .667 A

(a) The current I would be greater with A and C connected than without them connected. (b) Connecting A and C with a wire would have no effect on I. (c) The current I would be less with A and C connected than without them connected.

(a) 5 W (b) 1.67 W (c) 0.56 W

(a) 1 (b) 2 (c) 2.5 (d) 4 (e) 10

Which one of the following equations is true?

(a) I_{3} + I_{4} = I_{2} (b) I_{1} + I_{2} - I_{3} = 0 (c) I_{3} = - I_{4}

(a) 15 I_{1} + 12 + 16 I_{3} - 20 = 0 (b) -23 I_{1} + 12 - 16 I_{3} - 20 = 0 (c) 15 I_{1} + 8 I_{3} - 6 = 0

(T) True (F) False

The capacitor in this circuit is initially uncharged. At time t = 0, switch S_{1} is closed but switch S_{2} is left open.

What is the charge Q on the capacitor after a time equal to 2 time constants (t = 2τ) has elapsed?

(a) 14.6 μC (b) 16.9 μC (c) 108 μC

(a) 13.3 mA (b) 24 mA (c) 30 mA

(a) If S_{2} is closed, the capacitor will charge faster. (b) If S_{2} is open, the capacitor will charge faster. (c) S_{2} has no effect on the rate at which the capacitor charges.