ASVAB ASVAB Electronics Fundamentals and Circuits 5

Question 1

A circuit has a 10Ω resistor and a 10Ω inductive reactance connected in series. What is the impedance?

Accepted Answer

14.14Ω

Answer

Impedance Z = √(R² + XL²) = √(100 + 100) = √200 ≈ 14.14Ω.

Question 2

What happens to the resonant frequency of an LC circuit if the inductance is increased fourfold while capacitance stays the same?

Accepted Answer

It is halved

Answer

Resonant frequency f = 1/(2π√LC); quadrupling L makes √(4L) = 2√L, so frequency is halved.

Question 3

Which semiconductor device is commonly used as a voltage-controlled switch in digital logic circuits?

Accepted Answer

MOSFET

Answer

MOSFETs are the dominant switching device in digital logic because they are voltage-controlled and have very high input impedance.

Question 4

What is the purpose of a bypass capacitor placed across a power supply rail in an amplifier circuit?

Accepted Answer

Filter out AC ripple and high-frequency noise from the supply voltage

Answer

Bypass capacitors provide a low-impedance path to ground for AC noise on the DC supply rail, keeping the supply clean.

Question 5

A 120V RMS AC source is applied across a circuit. What is the approximate peak voltage?

Accepted Answer

170V

Answer

Peak voltage = RMS × √2 ≈ 120 × 1.414 ≈ 170V.

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