If the magnitude difference between one star and another is 5, the stars differ in brightness by a factor of
a. 2.51.
b. 10.
c. 4.
d. 100.
[Ques. 2] When fast electrons strike a metal target, what are produced?
a. Radio waves
b. Gamma rays
c. X-rays
d. Microwaves
[Ques. 3] 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 impedance is
a. 4.68 .
b. 8.84 .
c. 10.0 .
d. 13.4 .
e. 18.8 .
[Ques. 4] If the magnitude difference between one star and another is 1, the stars differ in brightness by a factor of
a. 10.
b. 100.
c. 2.51.
d. 4.
[Ques. 5] Wilhelm Roentgen discovered
a. X-rays.
b. gamma rays.
c. radio waves.
d. microwaves.
[Ques. 6] 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 peak current in the circuit is
a. 8.24 A.
b. 8.84 A.
c. 11.0 A.
d. 12.4 A.
e. 23.5 A.
[Ques. 7] Stars of what magnitude are just barely visible to the unaided eye?
a. 4
b. 6
c. 2
d. 0
[Ques. 8] The interior of a large mass of food in a microwave oven must be heated mainly by
a. radiation.
b. conduction.
c. convection.
d. radioactivity.
[Ques. 9] The average power input to a series alternating current circuit is minimum when
a. there are only a resistor and capacitor in the circuit.
b. there are only a resistor and inductor in the circuit.
c. there is only a resistor in the circuit.
d. XL = XC and the circuit contains a resistor, an inductor and a capacitor.
e. there is only a capacitor in the circuit.
[Ques. 10] Antiquity's greatest observer of stars was named
a. Hipparchus.
b. Eratosthenes.
c. Aristotle.
d. Imhotep.
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