Which one of the following is an example of a blackbody that you see in everyday life?
A. a stove burner
B. a fluorescent light
C. a laser pointer
D. a neon light
Answer: A
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A wheel is rotated about a horizontal axle at a constant angular speed. Next it is rotated in the opposite direction with the same angular speed. The acceleration at a point on the top of the wheel in the second case as compared to the acceleration in the first case:
a. is in the same direction. b. is in the opposite direction. c. is upward. d. is tangential to the wheel.
A long, fine wire is wound into a coil with inductance 5 mH. The coil is connected across the terminals of a battery, and the current is measured a few seconds after the connection is made. The wire is unwound and wound again into a different coil with L = 10 mH. This second coil is connected across the same battery, and the current is measured in the same way. Compared with the current in the
first coil, the current in the second coil is: 1.four times as large. 2.twice as large. 3.unchanged. 4.half as large. 5.one-fourth as large.
In order to conserve fuel, you modify your car by removing 100 kg of excess weight. How much energy is saved each time you drive up a 3 km high mountain?
a. 
b. 
c. 
d. 
The electric field at the surface of a conductor is
A) always zero. B) perpendicular to the surface. C) parallel to the surface. D) never zero.