CBSE TEST PAPER-01

CLASS - XII PHYSICS (Electromagnetic Induction and Alternating current)

1. A metallic wire coil is stationary in a non – uniform magnetic field. What is the

emf. Induced in the coil?

[1]

2. Why does metallic piece becomes very hot when it is surrounded by a coil

carrying high frequency (H.F) alternating current?

[1]

3. IF the rate of change of current of 2A/s induces an emf of 1omV in a solenoid.

What is the self inductance of the solenoid?

[1]

4. A circular copper disc. 10 cm in radius rotates at a speed of 2

axis through its centre and perpendicular to the disc. A uniform magnetic field

of 0.2T acts perpendicular to the disc.

1) Calculate the potential difference developed between the axis of the disc

and the rim.

2) What is the induced current if the resistant of the disc is 2

[3]

5. How is the mutual inductance of a pair of coils affected when

(1) Separation between the coils is increased.

(2) The number of turns of each coil is increased.

(3) A thin iron sheet is placed between two coils, other factors remaining the

same. Explain answer in each case.

[3]

6. Distinguish between resistances, reactance and impedance of an a.c. circuit? [3]

7. A sinusoidal voltage V = 200 sin 314t is applied to a resistor of 10

p rad/s about anW?W

resistance. Calculate

(1) rms value of the voltage

(2) rms value of the current

(3) Power dissipated as heat in watt.

[3]

8. (a) State the condition under which the phenomenon of resonance occurs

in a series LCR circuit. Plot a graph showing the variation of current

with frequency of a.c. sources in a series LCR circuit.

(b) Show that in a series LCR circuit connected to an a.c. source exhibits

resonance at its natural frequency equal to

1/(LC)?

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