NETA AC/DC Theory and Circuits 4

Question 1

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

Accepted Answer

Capacitive and inductive reactances are equal and cancel

Answer

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

Question 2

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

Accepted Answer

0.5 seconds

Answer

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

Question 3

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

Accepted Answer

96 V

Answer

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

Question 4

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

Accepted Answer

90°

Answer

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

Question 5

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

Accepted Answer

Parallel circuit

Answer

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

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