Motional Emf: As shown in the figure, a straight wire carries a steady current I. A metal bar is in contact with a pair of rails and is in upward motion with velocity of magnitude ?. The polarity of the induced emf in terminals X and Y is
A. X and Y are at the same potential.
B. X is positive and Y is negative.
C. Y is positive and X is negative.
Answer: C
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A uranium atom is 238 times as massive as a hydrogen atom. Compared with the diameter of a hydrogen atom, uranium's size is
A) slightly smaller. B) only slightly larger. C) is much larger, but less than 238 times as large.
Fraunhofer lines are apparent in
A) absorption spectra. B) emission spectra. C) Doppler shifts. D) a variety of energy levels. E) none of the above
A gas expands from an initial volume of 0.040 m3 to a final volume of 0.085 m3 while its pressure increases linearly with the volume (so that the process follows a straight-line path in a pV diagram) from 110 kPa to 225 kPa
How much work is done on the gas during this expansion? A) -5.2 kJ B) -7.5 kJ C) -7.8 kJ D) -11 kJ E) -12 kJ
The coefficient of linear expansion of copper is 17 × 10-6 K-1. A block of copper 30 cm wide, 45 cm long, and 10 cm thick is heated from 0°C to 100°C What is the change in the volume of the block?
A) 2.3 × 10-5 m3 B) 6.9 × 10-5 m3 C) 5.2 × 10-5 m3 D) 4.6 × 10-5 m3 E) 14 × 10-5 m3