Two point charges are 12 cm apart. They are moved to a new separation of 3 cm. By what factor does the resulting mutual force between them change?
a. 1/4
b. 4
c. 1/16
d. 16
e. 4.5
[Ques. 2] An AC series circuit has 18.9- resistance, 21.1- inductive reactance, and 15.5- capacitive reactance. If an effective (rms) emf of 94 V is applied, what is the power output?
a. 2.34E+2 W
b. 1.60E+2 W
c. 4.66E+2 W
d. 4.30E+2 W
e. 2.32E+2 W
[Ques. 3] Object A has a charge q on it, object B has a charge q on it, and object C has a charge 3q on it. These charges are arranged, one each, at the vertices of an equilateral triangle. Which charge has the greatest magnitude electric force on it?
a. A
b. B
c. C
d. All have equal magnitude forces on them.
e. A and B
[Ques. 4] A 104- resistor is connected in series with a 14.7-F capacitor and a 56-Hz, 136-V (rms) line voltage. If electrical energy costs 4.8 per kWh, about how much does it cost to leave this circuit connected for 24 hours?
a. 2
b. 46
c. 200
d. 5
[Ques. 5] About how many electrons are in 40 grams of water (H2O)?
a. 4E+26
b. 2E+25
c. 1E+24
d. 2E+22
e. 4E+27
[Ques. 6] What is the average power dissipation in a series RC circuit if R = 6.35 k, C = 2.64 F, and V = (192 V) cos 115t?
a. 2.29 W
b. 5.81 W
c. 2.90 W
d. 3.23 W
e. 6.47 W
[Ques. 7] If a negative charge is placed inside a hollow isolated conductor that is originally neutral and the charge does not touch that conductor at any time:
a. both the inner and outer surfaces will become negative.
b. both the inner and outer surfaces will remain neutral.
c. the outside surface of the conductor will become positively charged.
d. the inside surface of the conductor will become positively charged.
[Ques. 8] The power dissipated in an AC series circuit increases as the phase angle approaches what value?
a. zero
b. 45
c. 90
d. 180
[Ques. 9] The charge per unit length on an insulator is 6.2 C/m. On a 2.0-m length of this material, what is the difference in the number of electrons and the number of protons?
a. There are 7.8 1013 more electrons than protons.
b. There are 7.8 1013 more protons than electrons.
c. There are 3.9 1013 more protons than electrons.
d. There are 3.9 1013 more electrons than protons.
[Ques. 10] An electric motor produces 2.0 hp in a Vrms = 120 V circuit. What is Irms for this motor? (1 hp = 746 W)
a. 12 A b. 6.2 A
c. 0.62 A d. 1.6 A
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