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 144. The exam period was 90 minutes; the mean was 110.7; the median was 114. 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}.

The intensity of the sunlight that reaches Earth's atmosphere is approximately 1400 W/m^{2}.

What is the average energy density u of the sunlight?

(a) u = 8.1 × 10^{-9} J/m^{3} (b) u = 4.7 × 10^{-6} J/m^{3} (c) u = 4.7 × 10^{-3} J/m^{3} (d) u = 9.0 × 10^{3} J/m^{3} (e) u = 5.8 × 10^{6} J/m^{3}

(a) E_{rms} = 1.2 mV/m (b) E_{rms} = 7.0 V/m (c) E_{rms} = 730 V/m (d) E_{rms} = 9.1 kV/m (e) E_{rms} = 34000 kV/m

Light linearly polarized in the x-direction shines through two polarizers. The first polarizer's transmission axis makes an angle θ with the x-axis and the transmission axis of the second is parallel to the y-axis.

If the incident light has intensity I_{0}, what is the intensity of the light transmitted through the second sheet, I_{2,}, for any θ ?

(a) I_{2} = 0 (b) I_{2} = I_{0} cos^{4}θ (c) I_{2} = I_{0} cos^{2}θ sin^{2}θ (d) I_{2} = I_{0} sin^{4}θ (e) I_{2} = I_{0}

(a) I_{2 }does not depend on θ. (b) θ = 0° (c) θ = 30° (d) θ = 45° (e) θ = 60°

If the light that emerges from the system has an intensity of 23.0 W/m^{2}, what is the intensity of the incident light I_{0} ?

(a) I_{0} = 95.7 mW/m^{2} (b) I_{0} = 65.7 W/m^{2} (c) I_{0} = 96.4 W/m^{2} (d) I_{0} = 15.7 kW/m^{2} (e) I_{0} = 97.0 kW/m^{2}

Two polarizers are placed with their transmission axes at right angles to each other. A third polarizer is placed between them with its transmission axis at 45° to the axes of the other two.

If unpolarized light of intensity I_{0} is incident on the system, what is the intensity of the transmitted light I_{3} ?

(a) I_{3} = I_{0} / 8 (b) I_{3} = I_{0} / sqrt(3) /2 (c) I_{3} = I_{0} × 2 / sqrt(3) (d) I_{3} = I_{0} (e) I_{3} = 0

(a) I_{3} = I_{0} / 8 (b) I_{3} = I_{0} / sqrt(3) / 2 (c) I_{3} = I_{0} × 2 / sqrt(3) (d) I_{3} = I_{0} (e) I_{3} = 0

Abraham Lincoln is standing in front of a mirror, wearing a tall hat. The distance h from his toes to the top of his hat is 220 cm.

What is the minimal vertical length m of a plane mirror in which Lincoln can see his full image (from his toes to the top of his hat)?

(a) m = 80 cm (b) m = 110 cm (c) m = 220 cm (d) Any mirror size will be sufficient. (e) No mirror size will be sufficient.

(a) x = 80 cm (b) x = 110 cm (c) x = 220 cm (d) Any distance will be sufficient. (e) No distance will be sufficient.

For what angle θ is the final ray horizontal?

(a) θ = 30° (b) θ = 40° (c) θ = 45° (d) θ = 70° (e) Any value of θ will yield a horizontal final ray.

A radio tuner has a 400 Ω resistor, a 0.5 mH inductor, and a variable capacitor, all connected in series. Suppose the capacitor is adjusted to 72 pF.

What is the resonant frequency f_{o} of the circuit?

(a) f_{o} = 50 Hz (b) f_{o} = 120 Hz (c) f_{o} = 840 kHz (d) f_{o} = 5.3 MHz (e) f_{o} = 102 MHz

(a) X_{L} = 0 kΩ (b) X_{L} = 0.4 kΩ (c) X_{L} = 0.8 kΩ (d) X_{L} = 2.6 kΩ (e) X_{L} = 5.4 kΩ

(a) I_{rms} = 0 mA (b) I_{rms} = 0.05 mA (c) I_{rms} = 0.12 mA (d) I_{rms} = 0.45 A (e) I_{rms} = 5A

(a) C = 25 pF (b) C = 72 pF (c) C = 95 μF (d) C = 34 μF (e) C = 48 mF

Light (λ = 500 nm in air) impinges at normal incidence from air (n = 1) onto a thin plastic film (n = 1.4) of thickness t which is on top of a thick glass plate (n = 1.5).

Find the minimum (non-zero) thickness t of the film which gives constructive interference.

(a) t = 75 nm (b) t = 107 nm (c) t = 178 nm (d) t = 214 nm (e) t = 300 nm

(a) constructively. (b) destructively.

(a) remain the same. (b) change to the opposite choice.

An object of height 5 cm is at a position 15 cm away from a spherical concave mirror. The image is located 30 cm to the left of the mirror.

What is the focal length of the mirror?.

(a) 5 cm (b) 10 cm (c) 15 cm (d) 20 cm (e) 25 cm

(a) 2.5 cm (b) 5.0 cm (c) 10 cm

(a) upright. (b) inverted.

Which ray in this ray diagram is not correct?

(a) 1 (b) 2 (c) 3

(a) to the left of the left focal point (b) between the left focal point and the lens (c) between the right focal point and the lens (d) at the right focal point (e) to the right of the right focal point

(a) +1. (b) +0.33 (c) -0.33 (d) +0.67 (e) -0.67

A man requires bifocals to correct both his near and far vision problems. Consider the bifocals to be a pair of glasses with a "main" lens and an additional "add-on" lens placed at the bottom. The main lens corrects his vision of distant objects. The add-on lens corrects his vision for reading.

Which of the following figures qualitatively represents the lenses in a pair of bifocals as described above?

(a) (b) (c)

(a) 41.7 cm (b) 53.9 cm (c) 66.3 cm

(a) | P | = 1.05 diopters (b) | P | = 1.09 diopters (c) | P | = 1.14 diopters (d) | P | = 1.23 diopters (e) | P | = 1.40 diopters

In what medium does the light travel the fastest?

(a) medium with index n_{1} (b) medium with index n_{2} (c) medium with index n_{3}

In the figure to the right, a light beam starts from the lower left corner in air, enters a box with a transparent material inside, strikes a mirror and reflects, then exits the box back into the air along the direction shown.

For n_{stuff} = 1.5, calculate L.

(a) L = 6.39 cm (b) L = 7.14 cm (c) L = 8.05 cm (d) L = 8.88 cm (e) L = 9.32 cm

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