Class 12 Alternating Current CBSE Questions & Answers

A resistor of 100 \(\Omega \) and a capacitor of 10\(\mu \)F are connected in series to a 220 V 50 Hz ac source. Voltage across the capacitance and resistor are

A sinusoidal voltage of peak value 283 V and frequency 50 Hz is applied to a series LCR circuit in which R = 3 \(\Omega \), L = 25.48 mH, and C = 796 \(\mu {\rm{F}}\). Power dissipated in the circuit; and the power factor are

In the free oscillations of an LC circuit, the sum of energies stored in the capacitor and the inductor.

A series LCR circuit with R = 20 \(\Omega \), L = 1.5 H and C = 35 \(\mu {\rm{F}}\) is connected to a variable-frequency 200 V ac supply. When the frequency of the supply equals the natural frequency of the circuit average power transferred to the circuit in one complete cycle iss

A radio can tune over the frequency range of a portion of MW broadcast band: (800 kHz to 1200 kHz). If its LC circuit has an effective inductance of 200 \(\mu {\rm{H}}\), what must be the range of its variable capacitor?

Series LCR circuit is connected to a variable frequency 230 V source. L = 5.0 H, C = 80 \(\mu {\rm{F}}\), R = 40 \(\Omega \). Impedance of the circuit and the amplitude of current at the resonating frequency are

An LC circuit contains a 20 mH inductor and a 50 \(\mu {\rm{F}}\) capacitor with an initial charge of 10 mC. The resistance of the circuit is negligible. Natural frequency of the circuit is

A coil of inductance 0.50 H and resistance 100 \(\Omega \) is connected to a 240 V, 50 Hz ac supply.Maximum current in the coil and time lag between the voltage maximum and the Current maximum are

A 100 μF capacitor in series with a 40 \(\Omega \) resistance is connected to a 110 V, 60 Hz supply. Maximum current in the circuit and time lag between the current maximum and the voltage maximum are

A circuit containing a 80 mH inductor and a 60 \(\mu {\rm{F}}\) capacitor in series is connected to a 230 V, 50 Hz supply. The resistance of the circuit is negligible. Average powers transferred to the inductor and to the capacitor are respectively

Resonant frequency and Q-factor of a series LCR circuit with L = 3.0 H, C = 27 \(\mu {\rm{F}}\), and R = 7.4 \(\Omega \) are respectively

A power transmission line feeds input power at 2300 V to a step-down transformer with its primary windings having 4000 turns. Number of turns in the secondary in order to get output power at 230 V is

A small town with a demand of 800 kW of electric power at 220 V is situated 15 km away from an electric plant generating power at 440 V. The resistance of the two wire line carrying power is 0.5 \(\Omega \) per km. The town gets power from the line through a 4000-220 V step-down transformer at a sub-station in the town. Line power loss in the form of heat is

A small town with a demand of 800 kW of electric power at 220 V is situated 15 km away from an electric plant generating power at 440 V. The resistance of the two wire line carrying power is 0.5 \(\Omega \) per km. The town gets power from the line through a 4000-220 V step-down transformer at a sub-station in the town. Power that the plant supply, assuming there is negligible power loss due to leakage is

The current amplitude in a pure inductor in a radio receiver is to be 250 \(\mu {\rm{A}}\) when the voltage amplitude is 3.60 V at a frequency of 1.60 MHz (at the upper end of the AM broadcast band). Inductive reactance needed is