AC/DC Theory and Circuits Flashcards

In a series RLC circuit at resonance, which statement is true?

Answer: Capacitive and inductive reactances are equal and cancel

At resonance, XL equals XC, so they cancel and the circuit impedance equals only the resistance R.

What is the time constant (τ) for a series RC circuit with R = 10 kΩ and C = 50 µF?

Answer: 0.5 seconds

τ = RC = 10,000 Ω × 50×10⁻⁶ F = 0.5 seconds.

A transformer has 500 primary turns and 100 secondary turns. If the primary voltage is 480 V, what is the secondary voltage?

Answer: 96 V

Vs = Vp × (Ns/Np) = 480 × (100/500) = 96 V.

In a purely capacitive AC circuit, the current leads the voltage by:

Answer: 90°

In a purely capacitive circuit, current leads voltage by exactly 90° (π/2 radians).

Which type of circuit connection results in the same voltage across each element but different currents?

Answer: Parallel circuit

In a parallel circuit, all branches share the same voltage while current divides among the branches.

The quality factor (Q) of an inductor is defined as the ratio of:

Answer: Inductive reactance to resistance

Q = XL / R, representing how efficiently an inductor stores energy relative to its losses.

When measuring DC voltage with a digital multimeter across a 24 V battery showing 22.8 V, what does this most likely indicate?

Answer: The battery is partially discharged

A reading of 22.8 V on a nominal 24 V battery indicates the battery is partially discharged but not critically low.