A 10-mH inductor is connected in series with a 10-ohm resistor, a switch and a 6-volt battery. What is the time constant of the circuit? How long after the switch is closed will the current reach 99 percent of its final value?
[Ques. 2] The explosion of a Type II supernova leaves behind
a. just a black hole.
b. a neutron star or a black hole.
c. just a neutron star.
d. none of the above.
[Ques. 3] According to the Bohr theory, the probability of finding a hydrogen atom's ground-state electron 0.053 nm from the proton is
a. low, but not zero.
b. 100.
c. zero.
d. high, but not 100.
[Ques. 4] Find the magnetic energy stored in the air gap between two very large magnetic pole pieces, one North, one South, each with an area of 100 cm2 . Assume the 0.05 T magnetic field is uniform within the 2-cm gap.
[Ques. 5] A faint white dwarf that temporarily increases in brightness as a consequence of nuclear explosions on its surface is termed
a. a nova.
b. a Type II supernova.
c. a bright nebula.
d. a red giant.
[Ques. 6] According to the Schrdinger equation, the probability of finding a hydrogen atom's ground-state electron 0.053 nm from the proton is
a. zero.
b. high, but not 100.
c. low, but not zero.
d. 100.
[Ques. 7] The magnetic field in a superconducting solenoid is 3.0 T. How much energy per unit volume is stored in the solenoid, in J/m3? 0 = 4 107 T A/m
[Ques. 8] The radial distance to the event horizon from the singularity of a black hole is called
a. the Roche limit.
b. the Schwarzschild radius.
c. the Hubble unit.
d. none of the above.
[Ques. 9] Which phenomenon shows that quanta of light, or photons, exist?
a. Diffraction
b. Polarization
c. The photoelectric effect
d. Interference
[Ques. 10] After a switch is thrown to remove the battery from a DC LR circuit, but the circuit is still left complete, the time constant represents
a. the time rate of change of the current in the circuit.
b. the time rate of change of the induced emf in the circuit.
c. the magnitude of the ratio of the current to the time rate of change of the current.
d. all of the above.
e. only (a) and (b) above.
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