A 60.0-Hz ac generator with a peak voltage of 110 V drives a series RL circuit with R = 10.0 and L = 10.0 mH. The power factor, cos , is
a. 1.00.
b. 0.936.
c. +0.943.
d. +0.936.
e. +1.00.
[Ques. 2] The brightest star (apparent magnitude 1) in the night sky in the Northern Hemisphere is named
a. Polaris.
b. Sirius.
c. Deneb.
d. Alpha Centauri.
[Ques. 3] According to the hypothesis of de Broglie, any moving particle has
a. energy.
b. a magnetic force field.
c. an electric force field.
d. a wavelength.
[Ques. 4] A 60.0-Hz ac generator with a peak voltage of 110 V drives a series RL circuit with R = 10.0 and L = 10.0 mH. The impedance is
a. 3.77 .
b. 9.26 .
c. 10.0 .
d. 10.7 .
e. 13.8 .
[Ques. 5] If the magnitude difference between one star and another is 7, the stars differ in brightness by a factor of
a. 2.51.
b. 18.
c. 6.
d. 628.
[Ques. 6] The key process of a laser is
a. stimulated emission.
b. Bremsstrahlung.
c. electron diffraction.
d. microwave absorption.
[Ques. 7] A 60.0-Hz ac generator with a peak voltage of 110 V drives a series RL circuit with R = 10.0 and L = 10.0 mH. The peak current in the circuit is
a. 0.963 A.
b. 10.3 A.
c. 11.0 A.
d. 11.9 A.
e. 29.2 A.
[Ques. 8] If the magnitude difference between one star and another is 8, the stars differ in brightness by a factor of
a. 2.51.
b. 20.
c. 7.
d. 1580.
[Ques. 9] When many of the atoms or molecules in a sample have been excited into a metastable state, a(n) ______________ has occurred.
a. ultraviolet catastrophe
b. population inversion
c. coherent emission
d. incoherent absorption
[Ques. 10] A 60.0-Hz ac generator with a peak voltage of 110 V drives a series RC circuit with R = 10.0 and C = 300 F. The power factor, cos , is
a. 1.00.
b. 0.749.
c. +0.749.
d. +0.834.
e. +1.00.
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