CBSE Class 12 Physics Alternating Current Objective Questions

CBSE Class 12 Physics Alternating Current Objective Questions. Please refer to the examination notes which you can use for preparing and revising for exams. These notes will help you to revise the concepts quickly and get good marks.

1. A 10μ F capacitor is connected across a 200 V, 50 Hz a.c. supply. The peak current through the circuit is
(a) 0.6 amp (b) 0.6 √2 amp (c) (0.6 / √2) amp (d) (0.6 π/2) amp.

2. In a L R circuit the a.c. source has voltage 220 V and the potential difference across the inductance is 176 volts. The potential difference across the resistance will be
(a) 44 V (b) 396 V (c) 132 V (d) √[(250×176)] V

3. An a.c. voltage source E = 200 √2 sin 100 t is connected across a circuit containing an a.c. ammeter and capacitor of capacity 1μF. the reading of ammeter is
(a) 10 mA (b) 20 mA (c) 40 mA (d) 80 mA

4. A 12 Ω resistor and a 0.21 henry inductor are connected in series to an a.c. source operating at 20 volt,50 cycle. The phase angle between the current and source voltage is
(a) 3 tan^–1 (b)tan^–1 1/√3 (c) tan^–1 (5.5) (d) tan^–1 (1)

5. In order to obtain a time constant of 10 seconds in an R.C. circuit containing a resistance of 103 Ω, the capacity of the condenser should be
(a) 10 μF (b) 100 μF (c) 1000 μF (d) 10000 μF

6. An A.C. series circuit contains 40 Ω of resistance and 30 Ω of inductive reactance. Then the impedance of circuit is
(a) 70 Ω (b) 10 Ω (c) 50 Ω (d) 70 Ω

7. A group of electric lamps having a total power rating of 1000 watt is supplied by an a.c. voltage E = 200 sin (310 t + 60⁰). Then the r.m.s. value of the circuit current is
(a) 10 amp (b) 10 √2 amp (c) 20 amp (d) 20 √2 amp.

8. In the alternating current circuit shown in following figure, the currents through the inductor and the capacitor are 1.2 amp and 1.0 amp. respectively. The current drawn from the generator is

(a) 0.4 amp. (b) 0.2 amp. (c) 1.0 amp. (d) 1.2 amp.

9. An alternating voltage E=200 √2 sin 100 t, where V is in volt and t in seconds, is connected to a series combination of 1 μF capacitor and a 10 kΩ resistor through an ac ammeter. The reading of the ammeter will be
(a) 2 mA (b) 10 2 mA (c) 2 mA (d) 20 mA

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