Physics Class 12 NCERT Solutions: Chapter 7 Alternating Current Part 1

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The RMS value of AC voltage

The RMS Value of AC Voltage

Q: 1. A resistor is connected to a ac supply.

(A) What is the value of current in the circuit?

(B) What is the net power consumed over a full cycle?

Answer:

Resistance of the resistor,

Supply voltage,

Frequency,

(A) The value of current in the circuit is given as:

(B) The net power consumed over a full cycle is given as:

Q: 2. (A) The peak voltage of an supply is. What is the voltage?

(B) The value of current in an ac circuit is A. What is the peak current?

Answer:

(A) Peak voltage of the ac supply,

Voltage is given as:

(B) The value of current is given as:

Now, peak current is given as:

Q: 3. A inductor is connected to, supply. Determine the rms value of the current in the circuit.

Answer:

Inductance of inductor,

Supply voltage,

Frequency,

Angular frequency,

Inductive reactance,

Value of current is given as

Hence, the value of current in the circuit is.

Q: 4. A 60 capacitor is connected to a supply. Determine the value of the current in the circuit.

Answer:

Capacitance of capacitor,

Supply voltage,

Frequency,

Angular frequency,

Capacitive reactance

Value of current is given as:

Hence, the value of current is.

Q: 5. In Exercises and (Above examples), what is the net power absorbed by each circuit over a complete cycle. Explain your answer.

Answer:

In the inductive circuit,

Value of current,

Value of voltage,

Hence, the net power absorbed can be obtained by the relation,

Where,

Phase difference between V and I

For a pure inductive circuit, the phase difference between alternating voltage and current is.

Hence, i.e., the net power is zero.

In the capacitive circuit,

Value of current,

Value of voltage,

Hence, the net power absorbed can obtained as:

For a pure capacitive circuit, the phase difference between alternating voltage and current is.

Hence, i.e., the net power is zero.

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