ASVAB Electronics 3 — Questions and Answers
Question 1: A transformer has a primary winding of 500 turns and a secondary winding of 100 turns. If the primary voltage is 120V, what is the secondary voltage?
- 24V (Correct answer)
- 600V
- 12V
- 240V
Correct answer: 24V
The turns ratio (500:100 = 5:1) means the secondary voltage is 120V ÷ 5 = 24V.
Question 2: Which type of capacitor is polarized and must be connected with correct polarity in a circuit?
- Electrolytic (Correct answer)
- Ceramic disc
- Mica
- Film
Correct answer: Electrolytic
Electrolytic capacitors are polarized due to their construction and will be damaged if connected in reverse polarity.
Question 3: What is the function of a diode in an AC circuit when used as a half-wave rectifier?
- Allows current to flow in only one direction (Correct answer)
- Amplifies the AC signal
- Converts voltage to current
- Filters out high frequencies
Correct answer: Allows current to flow in only one direction
A diode passes current in only one direction, so it blocks the negative half-cycle of AC, producing pulsating DC.
Question 4: In a series RLC circuit at resonance, which statement is TRUE?
- Impedance is at minimum and equals R (Correct answer)
- Impedance is at maximum
- Current is at minimum
- Capacitive reactance exceeds inductive reactance
Correct answer: Impedance is at minimum and equals R
At resonance, XL equals XC and they cancel, leaving only resistance R as the total impedance.
Question 5: What does a multimeter measure when set to the 'ohms' setting?
- Resistance (Correct answer)
- Current
- Power
- Frequency
Correct answer: Resistance
The ohms setting measures electrical resistance; the meter applies a small voltage and measures the resulting current to calculate resistance.
Question 6: Which component is commonly used to regulate voltage in a power supply by maintaining a constant output voltage despite load changes?
- Zener diode (Correct answer)
- NPN transistor
- Inductor
- Rheostat
Correct answer: Zener diode
A zener diode is designed to operate in reverse breakdown at a specific voltage, making it ideal for voltage regulation.
Question 7: A circuit draws 3 amps from a 12V battery. What is the power consumed?
- 36 watts (Correct answer)
- 4 watts
- 15 watts
- 9 watts
Correct answer: 36 watts
Power (P) = Voltage (V) × Current (I) = 12V × 3A = 36 watts.
ASVAB Electronics 3
A transformer has a primary winding of 500 turns and a secondary winding of 100 turns.
If the primary voltage is 120V, what is the secondary voltage?