University of Hawaii, Manoa
Dept. of Physics & Astronomy

Instructor: Michael Nassir
Office: Watanabe Hall, Rm. 426, (808) 956-2922
E-mail: nassir @

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ANSWERS to MIDTERM #3 from FALL 2004

Part A

1. T, T, F, F, T, F
2a. A
2b. C
2c. B
3a. B
3b. B
3c. D
4a. F
4b. F
4c. A (technically, although E was also accepted)

Part B

1a. A
1b. mag = -2.0  (d_i = 120 cm)
1c. object: 15 cm tall, upright, 60 cm to left of lens center
image: 30 cm tall, inverted, 120 cm to right of lens center
include at least 2 of 3 principal rays: "P ray" (horizontal to lens, then angling downward through focus to right of lens); "M ray" (straight line directly through exact center of lens and continuing on to right side); "F ray" (angling downward through left-hand focus to lens, then horizontal on right side of lens)

2a. Ray passes straight (no bending) into prism on bottom edge; ray bends toward right as emerges from upper slanted side of prism
2b. emerges at 72.7 degrees from the normal (ray strikes inside of upper slanted side at theta_incident=45deg to the normal)
2c. critical angle = 38.7 degrees
2d. Ray passes straight (no bending) into prism on bottom edge; ray reflects (total internal reflection) fromupper slanted edge, staying inside prism, and reflecting directly to the right; ray passes straight (no bending) out of right side of prism

3a. 0.693 m
3b. two-slit diffraction maxima occur at: x = -1.56 m, 0.00 m, +1.56 m
3c. E (two-slit diffraction minima occur at: x = -2.88 m, -0.71 m, +0.71 m, +2.88 m)