Class 12 Physics Chapter 7 Alternating Current Solved Question Answers

1 Transformer works on the principle of:

A convertor

B invertor

C mutual induction

D self-induction

View Answer

Answer:mutual induction

2 In series resonant circuit:

A reactance is zero

B current is zero

C voltage is zero

D None of these

View Answer

Answer:None of these

3 An acceptor circuit is :

A series resonant circuit

B parallel resonant circuit

C LCR circuit

D None of these

View Answer

Answer:series resonant circuit

4 Energy dissipates in LCR circuit in :

A L only

B C only

C R only

D All of the above°

View Answer

Answer:R only

5 A broadcast circute broadcasts at 300 m band. A condenser of capacitance 2.4 lµF is available. The value of the inductance required for resonant circuit is:

A 10^-4 H

B 10^-8 H

C 10^-6 H

D 10^-2 H

View Answer

Answer:10^-8 H

6 An iron core transformer with a turns ratio of 8 : 1 has 120 V applied across the primary. The voltage across the

A 15 V

B 120 V

C 180 V

D 960 V

View Answer

Answer:15 V

7 The dimensional formula of L/R is similar to that of:

A frequency

B time

C length

D none of these

View Answer

Answer:time

8 The dimensional formula of impedance is;

A [ML²T^-2A^-2]

B [ML²T^-3A^-2]

C [ML²T^-2A^-1]

D [ML²T^-2A^-3]

View Answer

Answer:[ML²T^-3A^-2]

9 Power factor of an ac circuit is a measure of:

A virtual power

B power lost in the circuit

C mean power

D all the above

View Answer

Answer:power lost in the circuit

10 Which of the following has dimensions different from the rest?

A L/R

B 1/RC

C √LC

D RC

View Answer

Answer:1/RC

11 What is the ratio of inductive and capacitance reactances in an ac circuit?

A 1

B ω²L

C ω²LC

D l

View Answer

Answer:ω²LC

12 In parallel resonant circuit:

A impedance is very high

B current is very high

C voltage is very high

D None of these

View Answer

Answer:impedance is very high

13 An ac ammeter connected in series in an ac circuit reads 5A. The peak value of current:

A 5 A

B 5√2A

C 5/√5 A

D zero

View Answer

Answer:5√2A

14 Which of the following effects is not shown in alternating current ?

A Chemical effect

B Magnetic effect

C Heating current

D All of these

View Answer

Answer:Chemical effect

15 An electric circuit containing capacitor only suffers:

A equal resistance for A.C. and D.C.

B Resistance of A.C. > Resistance of D.C.

C Resistance for A.C. < Resistance of D.C.

D offers infinite resistance for D.C.

View Answer

Answer:offers infinite resistance for D.C.

16 The average power dissipation in pure inductance or capacitance is:

A

B

C either (a) or (b)

D zero

View Answer

Answer:zero

17 The band width of a series resonant circuit is :

A f₀/Q₀

B R/2πL

C R/4πL

D 4R

View Answer

Answer:f₀/Q₀

18 The natural frequency of an L -C-Circuit is equal to :

A

B

C

D

View Answer

Answer:B

19 In series LCR circuit, the phase angle between supply voltage and current is

A

B

C

D

View Answer

Answer:A

20 Which of the following graphs represents the correct variation of inductive reactance X_L with frequency u?

A

Class 12 Physics Chapter 7 Alternating Current

B

C

D

View Answer

Answer:B

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NCERT Solutions for class 12 Physics | Chapter 7 - Alternating Current

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