# 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) 0

^{o }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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