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 was 76.0; the median was 78. Click here to see page1 page2 of the formula sheet that came with the exam.

(a) The charge on C_{1} decreases. (b) The charge on C_{1} stays the same. (c) The charge on C_{1} increases.

(a) (14/3) R (b) 4 R (c) (7/5) R (d) (4/3) R (e) (2/5) R

With the switch open as shown, what is the current I_{1}?

(a) I_{1} = -7/2 A (b) I_{1} = -1/2 A (c) I_{1} = 1/2 A (d) I_{1} = 3/2 A (e) I_{1} = 7/2 A

What is the voltage across the 4 ohm resistor?

(a) 6 V (b) 8 V (c) 14 V (d) 2 V (e) 7 V

(a) Only I_{3} has changed in magnitude. (b) Only I_{2} and I_{3} have changed in magnitude. (c) I_{1}, I_{2} and I_{3} have all changed in magnitude.

(a) R_{tot,1} > R_{tot,2} (b) R_{tot,1} < R_{tot,2} (c) R_{tot,1} = R_{tot,2}

At time t = 0 the switch is closed with the capacitor uncharged. The current through the capacitor right after the switch is closed is 0.0343 A.

What is the initial current through the 100 Ω resistor right after the switch is closed?

(a) 0.103 A (b) 0.069 A (c) 0.048 A

(a) 2.4 × 10^{-5} C (b) 4.8 × 10^{-5} C (c) 6.2 × 10^{-5} C (d) 7.2 × 10^{-5} C (e) 8.6 × 10^{-5} C

(a) 1.4 × 10^{-3} s (b) 1.5 × 10^{-3} s (c) 1.8 × 10^{-4} s

(a) 1.4 × 10^{-3} s (b) 1.5 × 10^{-3} s (c) 1.8 × 10^{-3} s

A square one-turn loop (side a = 20 cm, resistance R = 5 Ω, mass m = 200 g) located in the xy plane coasts with initial velocity v_{0} = 10 m/s in the x-y plane parallel to the x-axis in a region of no magnetic field as shown in the diagram. At time t = 0 s the loop enters a region of constant uniform magnetic field B = 1.5 T directed in the -z direction (into the page). In the following questions neglect any effect of magnetic fields that might be created by an induced current in the loop.

What is the magnitude of the EMF induced in the loop just after it enters the field? (Remember 1 mV = 10^{-3}V).

(a) EMF = 150 mV (b) EMF = 750 mV (c) EMF = 3 V

(a) clockwise (b) counterclockwise

(a) F = 4 a B v R (b) F = a^{2} B v R (c) F = a^{2} B^{2} v R (d) F = a^{2} B^{2} v / R (e) F = a^{2} B^{2} v^{2} / R

A tightly wound circular coil with radius a = 3 cm and N = 150 turns lies parallel to the x-y plane. The total resistance of the coil is 5 Ω. A spatially uniform magnetic field extends over the entire region of the coil and points in the +z direction (out of the page). The magnitude of the field varies with time as shown below (the maximum field B_{0} = 2 T is obtained at time t_{2} = 10 seconds). Neglect the effect of any B fields that might be created in the coil.

In what direction is the induced current flowing at time t_{1} = 5 seconds?

(a) I_{1} < I_{3} (b) I_{1} = I_{3} (c) I_{1} > I_{3}

(a) I_{1} = 12 mA (b) I_{1} = 17 mA (c) I_{1} = 38 mA (d) I_{1} = 52 mA (e) I_{1} = 85 mA

A generator consisting of a single loop of wire with area A is used to light a bulb with resistance R. The coil is rotated with constant angular velocity ω.

At which angle θ (as defined in the figure) is the flux through the loop largest?

(a) θ = 0° (b) θ = 45° (c) θ = 90°

An infinitely long wire carries a current I_{w} = 3.0 A (out of the page), and lies along the axis of symmetry of a cylindrical shell of inner radius a = 2.70 cm and outer radius b = 7.60 cm. The shell carries a current I_{2} = 1.8 A (into the page) distributed with uniform current density J.

Find the magnetic field strength at a distance r = 2.00 cm from the wire.

(a) B = 0 (b) B = 1.2 × 10^{-5} T (c) B = 1.8 × 10^{-5} T (d) B = 3.0 × 10^{-5} T (e) B = 4.8 × 10^{+5} T

(a) B = 2.9 × 10^{-6} T (b) B = 6.7 × 10^{-6} T (c) B = 8.2 × 10^{-6} T

(a) B = 2.7 × 10^{-6} T (b) B = 4.0 × 10^{-6} T (c) B = 0

An infinitely long wire carries a current I_{1} = 23 A. Another wire in the shape of a rectangular loop with sides a = 0.09 m and b = 0.20 m carries a current I_{2} = 15 A, and is placed near the infinitely long wire as shown in the figure below. (The side of the loop closest to the wire is a distance x = 0.01 m away from it.)

Calculate the z component of the magnetic field at the center of the rectangular loop (point P) due to the infinitely long wire.

(a) (b) (c)

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

(a) -x (b) +x (c) There is no direction since F = 0.

(a) emerge at the same position X, but after a different amount of time Δt. (b) emerge at a different position X, but after the same amount of time Δt. (c) emerge at a different position X and after a different amount of time Δt.