Practice Test: Question Set - 11
1. In an intrinsic semiconductor, the number of free electrons
- (A) Equals the
number of holes
- (B) Is less than
the number of holes
- (C) Is greater
than the number of holes
- (D) Impossible
to say
2. What is the power dissipation of a resistance that has 24 V dropped across it and 0.25 A flowing through it?
- (A) 3 W
- (B) 6 W
- (C) 64 W
- (D) 122 W
3. In a pure inductor:
- (A) AC current
leads the voltage by 90 degree
- (B) AC current
and voltage are exactly in phase
- (C) AC current
lags the voltage by 90 degree
- (D) AC current
is converted to dc voltage
4. Which one of the following phrases most accurately describes a purely capacitive circuit?
- (A) Resistances
provide the only opposition to current flow
- (B) Capacitive
reactance provides the only opposition to current flow
- (C) The ac
voltage leads the current by 90 degree
- (D) Combinations
of resistance and capacitive reactance provide any opposition to current flow
5. The equivalent of 1 micro A is:
- (A) 10000 A
- (B) 1000 A
- (C) One-millionth
of an ampere
- (D) One million
amperes
6. Which one of the following statements regarding ac circuits is correct?
- (A) Current and
voltages are in phase through a resistor
- (B) Current
leads the voltage through a resistor
- (C) Current lags
the voltage through a resistor
- (D) None of the
above
7. The rms value of a sine waveform is:
- (A) The number
of cycles completed in one second
- (B) The time
required to complete one full cycle
- (C) Equal to
0.707 times the peak amplitude
- (D) Equal to
1.41 times the peak amplitude
8. A real voltage source has
- (A) Zero
internal resistance
- (B) Infinite
internal resistance
- (C) A small
internal resistance
- (D) A large
internal resistance
9. What is the phase shift between total current and voltage in the circuit of a 100 ohm resistor connected in parallel with a capacitor that has a reactance of 100 ohm
- (A) 180 degree
- (B) 30
degree
- (C) 45
degree
- (D) 75
degree
10. Which one of the following statements is true for resistance in a parallel circuit?
- (A) The
total resistance is equal to the sum of the individual resistances in a
parallel circuit
- (B) The
total resistance of a parallel circuit is always less than the value of the
smallest resistance
- (C) The
total resistance of a parallel circuit is equal to the total voltage
- (D) The
total resistance in a parallel circuit is equal to the average value of the
individual resistances
11. The number of free electrons and holes in intrinsic semiconductor increases when the temperature
- (A) Decreases
- (B) Increases
- (C) Stays the
same
- (D) 0o C
12. What kind of battery is most likely included in a cordless electric knife?
- (A) Zinc-carbon
battery
- (B) Mercury-cell
battery
- (C) Nicad
battery
- (D) Lead-acid
battery
13. Which one of the following statements is true for the currents in a parallel RC circuit?
- (A) The
total current is equal to the sum of the currents for the resistance and
capacitance
- (B) The
current always has the same amplitude and phase for every part of the circuit
- (C) The
total current is less than the sum of the currents for the resistance and
capacitance
- (D) The
total current is greater than the sum of the currents for the resistance and
capacitance
14. Which one of the following statements is true?
- (A) Capacitive
reactance is at a minimum for dc source voltages
- (B) Capacitive
reactance decreases as the operating frequency increases
- (C) There
is no meaningful relationship between capacitive reactance and operating
frequency
- (D) Capacitive
reactance increases as the operating frequency increases
15. A device that converts mechanical into electrical energy is?
- (A) Solar cell
- (B) Thermocouple
- (C) Chemical
cell
- (D) Generator
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