ASVAB Electronics Fundamentals and Circuits Flashcards

A transformer has a primary winding of 200 turns and a secondary winding of 50 turns. If the primary voltage is 120V, what is the secondary voltage?

Answer: 30V

The turns ratio is 200:50 = 4:1, so secondary voltage = 120V ÷ 4 = 30V.

Which type of capacitor is polarized and must be installed with correct polarity?

Answer: Electrolytic capacitor

Electrolytic capacitors are polarized due to their oxide layer construction and will be damaged if installed backwards.

In a purely inductive AC circuit, the current lags the voltage by how many degrees?

Answer: 90°

In a purely inductive circuit, the inductor causes current to lag the applied voltage by exactly 90 degrees.

What does a diode's 'forward voltage drop' refer to?

Answer: The minimum voltage required for the diode to conduct in the forward direction

Forward voltage drop is the minimum voltage across a forward-biased diode needed for it to conduct; typically ~0.7V for silicon.

Two capacitors of 4μF and 12μF are connected in series. What is the total capacitance?

Answer: 3μF

Series capacitance: 1/C = 1/4 + 1/12 = 3/12 + 1/12 = 4/12, so C = 12/4 = 3μF.

What is the primary function of a zener diode in a circuit?

Answer: Regulate voltage by maintaining a constant reverse breakdown voltage

A zener diode is designed to operate in reverse breakdown, holding a steady voltage and thus regulating circuit voltage.

If a resistor is color-coded yellow, violet, orange, gold, what is its resistance value?

Answer: 47,000Ω ±5%

Yellow=4, Violet=7, Orange=×1000 multiplier → 47×1000 = 47,000Ω; Gold = ±5% tolerance.