# Physics Class 12 NCERT Solutions: Chapter 7 Alternating Current Part 1 (For CBSE, ICSE, IAS, NET, NRA 2022)

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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.