PHYSICS 152

University of Hawaii, Manoa Dept. of Physics & Astronomy

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

ANSWERS to FINAL EXAM from Fall 2003

Part A

1a. F
1b. B
1c. E
2a. E
2b. B
2c. E
3a. B
3b. A
3c. A
4. E
5. C
6a. B
6b. D
7. D

Part B

8. C
9a. A
9b. D
10. E
11. D
12. D (correction)
13. D (correction)
14. B
15. E (correction)
16a. B
16b. A
17. D
18. C
19. A

Part C

1a. To minimize currrent drawn from the voltage source, we want to maximize the total resistance of the 3 resistors (light bulbs). This is accomplished when the three are all connected in series with each other. (The equivalent resistance is then just the sum of the 3 resistances: 792 ohms.) I = 0.152 A is drawn from the voltage source.
1b. To maximize current drawn from the voltage source, we want to minimize the total resistance of the 3 resistors (light bulbs). This is accomplished when the three are all connected in parallel with each other. (The equivalent resistance then becomes 82.3 ohms.) The current drawn from the voltage source becomes 1.46 A.
1c. B = all light bulbs connected to the voltage source in parallel is the situation in household circuits
1d. C, B, A

2a. upward-curving path: alpha & beta-plus
straight path: gamma
downward-curving path: beta-minus
2b. (q/m) = 1.8x10^11 C/kg. The upward-curving path could be an alpha particle (q/m = 4.8x10^7 C/kg) or a beta-plus particle (positron) (q/m = 1.76x10^11 C/kg). Thus, our value of q/m is consistent with a positron.
2c. 2.27 hours or 136 min.

Part D

3a. +47 cm
3b. real, inverted, larger than object, same side of mirror as object
3c. ray diagram from object (given) to inverted image, -10 cm tall, located 47 cm to the left of the mirror
3d. virtual, upright, larger than object, opposite side of mirror from object

4a. 1.960 eV
4b. each photon carries 1.960 eV = 3.139x10^-19 J, so to emit 20 mW = 0.020 J/s, the laser must emit 6.4x10^16 photons/second
4c. 1.047x10^-27 (kg m)/s
4d. ("4e.") 66.3 nm, which lies in the ultraviolet