Page 47 - Physics - XII

Q2. The natural frequency of the circuit shown in Fig. is

(a) 1 C C
2π LC

1
(b)
2π 2LC L L

2
(c)
2π LC

(d) none of these

Q3. The resonant frequency ω of a series LCR circuit with L = 2 H, C = 32 µF, and R = 10 Ω is
r
(a) 125 rad s (b) 130 rad s (c) 135 rad s (d) 140 rad s –1
–1
–1
–1
Answer key
1. (b), 2. (a), 3. (a)

Assertion-Reason Based Questions

These consist of two statements—Assertion (A) and Reason (R). Answer these questions by selecting
the appropriate option given below:

a. Both A and R are true and R is the correct explanation of A.
b. Both A and R are true and R is not the correct explanation of A.
c. A is true but R is false.

d. A is false but R is true.

1. Assertion (A) : Capacitor serves as a block for D.C. and off ers an easy path to A.C.
Reason (R) : Capacitive reactance is inversely proportional to frequency.

2. Assertion (A) : In series LCR circuit, the resonance occurs at one frequency only.
Reason (R ) : At resonance, the inductive reactance is equal and opposite to the capacitive
reactance.
3. Assertion (A) : An alternating current does not show any magnetic eff ect.

Reason (R) : Alternating current does not vary with time.
4. Assertion (A) : Both A.C. and D.C. can be measured by hot wire instrument.

Reason (R) : Hot wire instrument is based on the principle of magnetic eff ect of current.

5. Assertion (A) : V RMS value of an alternating voltage V = 42 sin 314t is 4 volt.

Reason (R) : Peak value of the alternating voltage is 42 volt.

Answer key
1. (a), 2. (a), 3. (d), 4. (c), 5. (b)

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