# Alternating current MCQ Questions Class 12 Physics Chapter 7

Alternating current MCQ Questions Class 12 Physics Chapter 7

NCERT MCQ Questions for Class 12 Physics Chapter 7 Alternating current. Alternating current MCQ Questions with Answers from Class 12 Physics.

## Alternating current MCQ Questions Class 12 Physics Chapter 7

Alternating current Multiple Choice Questions with Answers Class 12 Physics Chapter 7 PDF is available.

1) The voltage which varies like a sine function with time is called as

a) DC voltage

b) AC voltage

c) Both a and b

d) None

Ans: b) AC voltage

2) The current driven by AC voltage is called as

a) DC current

b) Eddy current

c) AC current

d) None

Ans: c) AC current

3) The root mean square or effective current is given by

a) 0.707im

b) im/√2

c) 0.414im

d) Both a and b

Ans: d) both a and b

4) The phasors V and I for the resistance are in the same direction which means phase angle between the voltage and current is

a) Π

b) π/2

c) 0

d) None

Ans: c) 0

5) The quantity wL is analogous to resistance and it is called as

a) Capacitive reactance

b) Inductive reactance

c) Inductance

d) None

Ans: b) inductive reactance

6) The inductive reactance is given by

a) XL = w/L

b) XL= w/L2

c) XL= wL

d) XL= wL2

Ans: c) XL = wL

7) The SI unit of inductive reactance is

a) Ampere

b) Ohm

c) Volt

d) Henry

Ans: b) ohm

8) The inductive reactance is directly proportional to

a) Inductance L

b) Frequency of the current w

c) Both a and b

d) None

Ans: c) both a and b

9) The average power supplied to an inductor over one complete cycle is

a) Unity

b) Infinity

c) Constant

d) Zero

Ans: d) zero

10) 1/wC is called as

a) Inductive reactance

b) Capacitive reactance

c) Self inductance

d) Mutual inductance

Ans: b) capacitive reactance

11) The capacitive reactance is given by

a) Xc = wC

b) Xc= 1/wC

c) Xc= w/C

d) None

Ans: b) Xc= 1/wC

12) The SI unit of capacitive reactance is

a) Volt

b) Henry

c) Ohm

d) Ampere

Ans: c) ohm

13) The capacitive reactance is inversely proportional to

a) Frequency

b) Capacitance

c) Both a and b

d) None

Ans: c) both a and b

14) If the frequency is driven by an energy source at a frequency near the natural frequency then ____ takes place.

a) Mutual induction

b) Self induction

c) Resonance

d) None

Ans: c) resonance

15) In case of resonance the amplitude of oscillation is

a) Small

b) Medium

c) Large

d) Uniform

Ans: c) large

16) When Xc= XL then at that time frequency is called as

a) Natural frequency

b) System’s frequency

c) Resonant frequency

d) None

Ans: c) resonant frequency

17) At resonant frequency the impedance is

a) Maximum

b) Minimum

c) Both a and b

d) None

Ans: b) minimum

18) The resonant frequency is given by

a) 1/LC

b) 1/√LC

c) LC

d) None

Ans: b) 1/√LC

19) At resonant frequency current amplitude is

a) Minimum

b) Maximum

c) Both a and b

d) None

Ans: b) maximum

20) At resonant frequency

a) Impedance is minimum

b) Current amplitude is maximum

c) Both a and b

d) None

Ans: c) both a and b

21) WoL/R is called as

a) Resonant factor

b) Quality factor

c) Quantity factor

d) None

Ans: b) quality factor

22) The quantity Cosx is called as where X is the phase angle between voltage and current

a) Current factor

b) Voltage factor

c) Quality factor

d) Power factor

Ans: d) power factor

23) The circuit which contains only pure R is called as

a) Inductive circuit

b) LCR circuit

c) Resistive circuit

d) None

Ans: c) resistive circuit

24) For resistive circuit power factor is

a) 1

b) 0

c) -1

d) None

Ans: a) 1

25) The circuit which contains only an inductor is called as

a) Purely inductive

b) Resistive

c) Capacitive

d) LCR

Ans: a) purely inductive

26) The circuit which contains only capacitor is called as

a) Purely inductive

b) Purely capacitive

c) Purely resistive

d) None

Ans: b) purely capacitive

27) The power dissipation in purely resistive circuit is

a) Minimum

b) Zero

c) Maximum

d) Constant

Ans: c) maximum

28) The power factor for purely inductive or purely capacitive circuit is

a) 1

b) -1

c) Zero

d) Infinity

Ans: c) zero

29) In purely inductive or purely capacitive circuit the power dissipation is

a) Maximum

b) Minimum

c) Zero

d) No power dissipation

Ans: d) no power dissipation

30) The power dissipated at resonance in series LCR circuit is

a) Minimum

b) Maximum

c) Zero

d) None

Ans: b) maximum

31) The total energy of LC circuit is given by

a) q2C/2

b) q2/2C

c) 1/q2C

d) None

Ans: b) q2/2C

32) The transformer works on the principle of

a) Self induction

b) Mutual induction

c) Both a and b

d) None

Ans: b) mutual induction

33) In case of transformer the power input is equal to power output when

a) No energy losses

b) Transformer is 100% efficient

c) Both a and b

d) None

Ans: c) both a and b

34) If the secondary coil has less turns than primary then that transformer is called as

a) Step down transformer

b) Step up transformer

c) Both a and b

d) None

Ans: a) step down transformer

35) In step down transformer voltage is

a) Stepped down

b) Reduced

c) Increased

d) Both a and b

Ans: c) both a and b

36) In step down transformer the current is

a) Reduced

b) Increased

c) Remains same

d) None

Ans: b) increased

37) If the secondary coil has greater number of turns than the primary then that transformer is called as

a) Step down transformer

b) Step up transformer

c) Both a and b

d) None

Ans: b) step up transformer

38) In step up transformer, the voltage is

a) Stepped up

b) Reduced

c) Increased

d) Both a and c

Ans: d) both a and c

39) In step up transformer the current is

a) Increased

b) Decreased

c) Stepped up

d) None

Ans: b) decreased

40) Which of the following reasons for small energy losses in actual transformers

a) Flux leakage

b) Resistance of the windings

c) Hysterisis

d) All

Ans: d) all

41) Resonant frequency is measured in

a) Henry

b) Hertz

c) Volt

d) Meter

Ans: b) Hertz

42) The power rating of an element uses in an AC circuit refers to its

a) Power rating

b) Current power rating

c) Voltage power rating

d) Both b and c

Ans: c) voltage power rating

43) The device used to low voltage into high voltage and vice versa is called as

a) Voltmeter

b) Transistor

c) Transformer

d) Potentiometer

Ans: c) transformer

Updated: April 12, 2023 — 10:34 am