When a person stands 40 cm in front of a cosmetic (concave) spherical mirror, the upright image is twice the size of the object. What is the focal length of the mirror?
A) 27 cm
B) 40 cm
C) 80 cm
D) 160 cm
C
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An electronic game requires 6 V for operation. With a transformer it can be powered by a 120-V outlet. If the primary has 500 turns, the secondary has
A) 4 turns. B) 25 turns. C) 50 turns. D) more than 50 turns. E) none of the above
What happens to the magnitude of the magnetic field inside a long solenoid if the radius is doubled?
1.It becomes four times larger. 2.It becomes twice as large. 3.It is unchanged. 4.It becomes one-half as large. 5.It becomes one-fourth as large.
You are holding on to one end of a long string that is fastened to a rigid steel light pole. After producing a wave pulse that was 5 mm high and 4 cm wide, you want to produce a pulse that is 6 cm wide and 7 mm high. You must move your hand up and down once,
a. the same distance up as before, but take a shorter time. b. the same distance up as before, but take a longer time. c. a smaller distance up, but take a shorter time. d. a greater distance up, but take a longer time. e. a greater distance up, but take the same time.
An electron and a positron, which are two massive particles, can annihilate when they come together to produce two photons, which have no mass. According to special relativity, this pair annihilation is an example of __________
Fill in the blank(s) with correct word