A metal rod of length L moves with velocity v, perpendicular to its length, in a magnetic field B, which is perpendicular to both the rod and its velocity. If the length of the rod is doubled, what happens to the electric field in the rod?
A. it stays the same
B. it doubles
C. it quadruples
D. it halves
E. it quarters
A. it stays the same
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Nearly every aspect of astronomy is related in some way to the existence of gravity and to the motions which are responsible for a balance against gravity
How does this balance play a role for the miscellaneous objects of the solar system (i.e., the asteroids and comets)? How can some aspect of this be used as a tool to determine masses in the solar system?
What causes the radio pulses of a pulsar?
A) The star vibrates. B) As the star spins, beams of radio radiation sweep through space. If one of the beams crosses Earth, we observe a pulse. C) The star undergoes periodic explosions of nuclear fusion that generate radio emission. D) The star's orbiting companion periodically eclipses the radio waves emitted by the main pulsar. E) A black hole near the star absorbs energy and re-emits it as radio waves.
Tarzan swings back and forth on a long vine. His friend Jane notices in amazement that he makes 30 complete swings in 2.4 minutes
(a) What is the frequency (in hertz) of Tarzan's swing? (b) How long is the vine he is using?
In ?- decay, the number of neutrons in the nucleus is
A) decreased by 1. B) decreased by 2. C) increased by 1. D) increased by 2. E) remains unchanged.