This exam consists of 26 questions; 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 94. When the exam was given, the mean was 74.7; the median was 78. Click here to see page1 page2 of the formula sheet that came with the exam.

A conducting bar can slide along two fixed conductors which are separated by 1.3 m and connected by a resistor R = 12 Ω. A uniform magnetic field of 2.1 tesla points out of the page. The bar is allowed to fall due to gravity. The current passing through the circuit is measured to be 23 amperes.

What is the mass of the bar?

(a) 1.4 kg (b) 3.3 kg (c) 4.7 kg (d) 5.1 kg (e) 6.4 kg

(a) 98 m/s (b) 101 m/s (c) 115 m/s (d) 127 m/s (e) 133 m/s

(a) Does not change. (b) Increases. (c) Decreases.

(a) (b) (c)

Three parallel wires carry currents, equal in magnitude (I_{1} = I_{2} = I_{3} = 3 A) in the directions as shown.

What is the magnitude of the magnetic field at point x (0.5 meter below wire #1)?

(a) 9.2 × 10^{-6} T (b) 8.5 × 10^{-6} T (c) 5.3 × 10^{-6} T (d) 2.1 × 10^{-6} T (e) 1.5 × 10^{-6} T

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

(a) up (b) there is none (c) down

(a) 1.24 × 10^{-3} T (b) 2.08 × 10^{-3} T (c) 3.89 × 10^{-3} T

A long solenoid with 300 turns, a length of 0.25 meters, and a diameter of 2 cm has 100 mA of current passing through it in the direction shown below.

What is the magnetic field inside the solenoid?

(a) 9.83 × 10^{-5} T (b) 1.51 × 10^{-4} T (c) 6.00 × 10^{-4} T

(a) to the left (b) to the right

(a) smaller than the resonant frequency. (b) equal to the resonant frequency. (c) larger than the resonant frequency.

A square loop of wire, measuring 4 cm on each side is oriented in a 1.2 T magnetic field as shown. The loop has 0.35 amps flowing through it in a counter-clockwise direction. It is free to move in any direction.

How will the loop move in the field?

(a) to the left (b) to the right (c) rotate so that the left side comes out of the page and the right goes in (d) rotate so that the right side comes out of the page and the left goes in (e) it doesn’t move

(a) τ_{0} = 3.36 × 10^{-4} N-m (b) τ_{0} = 5.28 × 10^{-4} N-m (c) τ_{0} = 6.72 × 10^{-4} N-m

(a) τ_{0} sin(60°) (b) τ_{0} sin(30°) (c) τ_{0}

Consider the AC circuit shown below. The current through the generator is I(t) = 2.5 sin(377 t) amps.

Calculate V_{c}, the peak voltage across the capacitor.

(a) V_{c} = 375 volts (b) V_{c} = 442 volts (c) V_{c} = 5655 volts

(a) U_{L} = 0.594 J (b) U_{L} = 1.24 J (c) U_{L} = 2.49 J

(a) V_{gen} = 375 volts (b) V_{gen} = 423 volts (c) V_{gen} = 458 volts (d) V_{gen} = 823 volts (e) V_{gen} = 911 volts

(a) V_{L}(0) = 0 volts (b) V_{L}(0) = 78 volts (c) V_{L}(0) = 179 volts

Unpolarized light with intensity I_{0} is incident on a stack of three linear polarizers with transmission axis oriented as shown below.

Calculate I_{2}, the intensity of the light transmitted by the first two polarizers.

(a) I_{2} = 0 (b) I_{2} = ½ I_{0 }cos^{2}(30°) (c) I_{2} = ½ I_{0 }cos^{2}(60°)

(a) I_{3} = 0 (b) I_{3} = I_{2} cos^{2} (30°) (c) I_{3} = I_{2} cos^{2} (60°)

(a) decrease. (b) remain the same. (c) increase.

A mechanical crank is used to turn a rectangular loop with area 0.33 m^{2} at angular frequency ω in the presence of a magnetic field B = 0.8 T as shown. The 200 V peak EMF produced in the loop results in a peak voltage across the primary of the transformer of V_{p} = 200 V. The secondary windings are connected to an oscilloscope, and the peak voltage is 100 volts.

If the primary coil has 100 windings, how many windings are there in the secondary coil? (Note number of windings on picture is not accurate!)

(a) N_{s} = 50 (b) N_{s} = 100 (c) N_{s} = 200

(a) T = 2.3 ms (b) T = 3.6 ms (c) T = 4.1 ms (d) T = 8.3 ms (e) T = 9.8 ms

The electric field of an electromagnetic wave is given by the expression E(x,y,z,t) = 125 sin(15y - ωt) z volts/meter (in the z-direction).

Determine the wavelength λ of this electromagnetic wave.

(a) λ = 0.419 m (b) λ = 15 m (c) λ = 125 m

(a) x (b) y (c) z

(a) 0.75 × 10^{-8} J/m^{3} (b) 1.90 × 10^{-8} J/m^{3} (c) 3.45 × 10^{-8} J/m^{3}