NEET Physics Alternating Current MCQs

An AC voltage source with $V_{rms} = 100V$ is connected to a purely resistive load. If the peak instantaneous power delivered to the load is 200W, what is the average power delivered?

An AC circuit has a voltage $v(t) = 100\sin(100\pi t)$ and current $i(t) = 5\sin(100\pi t - \pi/3)$. What is the average power dissipated in the circuit?

A variable capacitor is connected to an inductor of inductance 20 mH. For what capacitance will the circuit resonate at a frequency of 1 kHz?

An LC circuit has a natural frequency of 50 kHz. If the capacitance is doubled and the inductance is halved, the new resonant frequency will be:

An ideal transformer has 100 turns in the primary and 500 turns in the secondary. If the primary voltage is 120V and the primary current is 2A, what is the secondary current?

A step-up transformer operates on a 220V line and supplies a load of 2A. The ratio of the primary and secondary windings is 1:25. Determine the current in the primary, assuming an ideal transformer.

A transformer has an efficiency of 80%. It works at 4 kW and 100 V. If the secondary voltage is 240 V, calculate the primary and secondary currents.

A 2200 V, 50 Hz AC source is connected to a series combination of a resistor $R$ and a choke coil $L$. If the voltage across the resistor is 120 V, and across the inductor is 1600 V, the power consumed by the choke coil is:

A series R-L-C circuit with $R = 10 \Omega$, $L = 0.1 H$, and $C = 10 \mu F$ is connected to an AC source with $V_{rms} = 200 V$ and variable frequency. At resonance, the average power dissipated in the circuit is:

A step-down transformer connected to an AC mains supply of 220 V operates a 11 V, 44 W lamp. Ignoring power losses, what is the current in the primary circuit?