Class 12 Physics MCQ Chapter 7 Alternation Current

Class 12 Physics MCQ Chapter 7 Alternation Current Solutions English Medium to each chapter is provided in the list so that you can easily browse through different chapters Class 12 Physics MCQ Chapter 7 Alternation Current Question Answer in English and select need one. AHSEC Class 12 Physics Objective Type Question Answer As Per AHSEC New Book Syllabus Download PDF. AHSEC Physics MCQ Class 12 Solutions.

Class 12 Physics MCQ Chapter 7 Alternation Current

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Also, you can read the NCERT book online in these sections Solutions by Expert Teachers as per Central Board of Secondary Education (CBSE) Book guidelines. AHSEC Class 12 Physics Multiple Choice Solutions in English Medium are part of All Subject Solutions. Here we have given AHSEC Class 12 Physics MCQ Question Answer English Medium for All Chapters, You can practice these here.

Alternation Current

Chapter: 7

Choose the correct option:

1. What is the most common application of LC oscillators?

(a) Radio transmitters.

(b) Switches.

(c) Torch.

(d) Fans.

Ans: (a) Radio transmitters.

2. The primary winding of a transformer has 500 turns whereas its secondary has 5000 turns The primary is connected to an a.c. supply of 20 V. 50 Hz. The secondary will have an output of:

(a) 2 V; 50 Hz.

(b) 200 V, 50 Hz.

(c) 200 V, 500 Hz.

(d) 2 V, 5 Hz.

Ans: (b) 200 V, 50 Hz.

3. In a pure capacitive circuit if the frequency of ac source is doubled, then its capacitive reactance will be:

(a) Remain same.

(b) Doubled.

(c) Halved.

(d) Zero.

Ans: (c) Halved.

4. A step-up transformer operates on 230 V line and supplies a load of 2 A. The ratio of primary and secondary turns is 1: 25 The current in the primary is:

(a) 50 A.

(b) 25 A.

(c) 15 A.

(d) 12.5 A.

Ans: (a) 50 A.

5. An alternating voltage E = 220 √2 sin 100 t is connected to 1 µF capacitor through an a.c. ammeter. The reading of the ammeter shall be:

(a) 22 mA.

(b) 10 mA.

(c) 40 mA.

(d) 80 mA.

Ans: (a) 22 mA.

6. Which of the following is usually taken to make the core of a transformer?

(a) Aluminium.

(b) Copper.

(c) Soft iron.

(d) Hard iron.

Ans: (c) Soft iron.

7. An a.c. circuit having an inductor and a resistor in series draws a power of 560 W from an a.c. source marked 210 V. 60 Hz. If power factor of the circuit is 0.8 then impedance of the circuit is:

(a) 103 Ω.

(b) 63 Ω.

(c) 12 Ω.

(d) 114 Ω.

Ans: (b) 63 Ω.

8. An alternating voltage E = 200 sin 300 t is applied across a series combination of R = 10 Ω and an inductor 800 mH. The power factor of the circuit is:

(a) 0.022

(b) 0.065

(c) 0.042

(d) 0.084

Ans: (c) 0.042.

9. Identify the principle behind the working of an a.c. generator.

(a) Eddy currents.

(b) Faraday’s law.

(c) Lenz’s law.

(d) Electromagnetic induction.

Ans: (d) Electromagnetic induction.

10. In an ac circuit, the current is i: 5 sin (100t – 𝜋/2) amp and the a.c. voltage is v=200 sin (100 t) volts. Then power consumption is:

(a) 200 W.

(b) 0 W.

(c) 40 W.

(d) 1000 W.

Ans: (b) 0 W.

11. In an a.c. circuit, the current:

(a) Is in phase with the voltage.

(b) Leads the voltage.

(c) All of the above.

(d) Any of the one depending upon circumstances.

Ans: (d) Any of the one depending upon circumstances.

12. Calculate the rms voltage, if the peak value of an a.c. supply is 300 V.

(a) 561.4 V.

(b) 969.2 V.

(c) 625.1 V.

(d) 212.1 V.

Ans:(d) 212.1 V.

13. In a circuit containing an inductance of zero resistance, the current leads the applied a.c. voltage by a phase angle of:

(a) 90°

(b) -90°

(c) 0°

(d) 180°

Ans: (b) -90°

14. In an a.c. circuit V and Ⅰ are given by: 

V100 sin (100 t) volts 

t =100 sin (100 t + π/3) mA 

The power dissipated in the circuit is:

(a) 104 W

(b) 10 W

(c) 2.5 W

(d) 5 W

Ans: (c) 2.5 W

15. Find out the net power consumed over a full cycle, if a 150 Ω resistor is connected to a 350 V, 100 Hz ac supply.

(a) 2.3 W.

(b) 350 W.

(c) 805 W.

(d) 500 W.

Ans: (c) 805 W.

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