ASVAB Electronics 4 — Questions and Answers
Question 1: What is the purpose of a bypass capacitor placed across a power supply pin on an integrated circuit?
- To filter out high-frequency noise on the supply line (Correct answer)
- To increase the supply voltage
- To slow down the circuit switching speed
- To convert AC to DC
Correct answer: To filter out high-frequency noise on the supply line
Bypass capacitors provide a low-impedance path to ground for high-frequency noise, keeping the supply voltage clean and stable.
Question 2: In a transistor amplifier circuit, what region of operation is the transistor in when it acts as a switch in the 'ON' state?
- Saturation (Correct answer)
- Cutoff
- Active
- Breakdown
Correct answer: Saturation
In saturation, both junctions are forward-biased and the transistor conducts maximally, acting like a closed switch.
Question 3: What is the unit of inductance?
- Henry (Correct answer)
- Farad
- Ohm
- Tesla
Correct answer: Henry
Inductance is measured in henries (H), named after Joseph Henry who discovered electromagnetic induction independently.
Question 4: Two resistors of 6Ω and 3Ω are connected in parallel. What is the equivalent resistance?
- 2Ω (Correct answer)
- 9Ω
- 4.5Ω
- 18Ω
Correct answer: 2Ω
For parallel resistors: 1/R = 1/6 + 1/3 = 1/6 + 2/6 = 3/6, so R = 2Ω.
Question 5: Which type of logic gate produces a HIGH output only when ALL inputs are HIGH?
- AND gate (Correct answer)
- OR gate
- NAND gate
- NOR gate
Correct answer: AND gate
An AND gate output is HIGH (1) only when every input is HIGH (1); any LOW input forces the output LOW.
Question 6: What happens to the capacitive reactance (XC) of a capacitor as frequency increases?
- It decreases (Correct answer)
- It increases
- It remains constant
- It becomes equal to resistance
Correct answer: It decreases
XC = 1/(2πfC), so as frequency (f) increases, XC decreases — capacitors pass high-frequency signals more easily.
Question 7: What is the primary purpose of a heat sink attached to a transistor or voltage regulator?
- To dissipate heat and prevent thermal damage (Correct answer)
- To increase the gain of the device
- To reduce electrical noise
- To filter the output signal
Correct answer: To dissipate heat and prevent thermal damage
Heat sinks increase surface area to transfer heat away from the component into the surrounding air, preventing overheating.
ASVAB Electronics 4
What is the purpose of a bypass capacitor placed across a power supply pin on an integrated circuit?