# Alternating Current MCQ Questions for Class 12 Physics Chapter 7 with Answers

Find here the NCERT chapter-wise Multiple Choice Questions from Class 12 Physics book Chapter 7 Alternating Current with Answers Pdf free download. This may assist you to understand and check your knowledge about the chapters. Students also can take a free test of the Multiple Choice Questions of Alternating Current. Each question has four options followed by the right answer. These MCQ Questions are selected supported by the newest exam pattern as announced by CBSE.

## Q1. Energy dissipates in LCR circuit in :

(i) L only
(ii) C only
(iii) R only
(iv) All of the above

(iii) R only

(i) 4 L
(ii) 2 L
(iii) L/2
(iv) L/4

(iii) L/2

## Q3. As the frequency of an ac circuit increases, the current first increases and then decreases. What combination of circuit elements is most likely to comprise the circuit?

(i) Inductor and capacitor.
(ii) Resistor and inductor.
(iii) Resistor and capacitor.
(iv) None.

(i) Inductor and capacitor.

## Q4. Alternating currents can be produced by a

(i) dynamo
(ii) choke coil
(iii) transformer
(iv) electric motor

(i) dynamo

(i) remains same
(ii) doubled
(iii) halved
(iv) zero

(iii) halved

## Q6. In an alternating current circuit consisting of elements in series, the current increases on increasing the frequency of supply. Which of the following elements are likely to constitute the circuit?

(i) Only resistor
(ii) Resistor and inductor
(iii) Resistor and capacitor
(iv) Only inductor

(iii) Resistor and capacitor

## Q7. The dimensional formula of L/R is similar to that of:

(i) frequency
(ii) time
(iii) length
(iv) none of these

(ii) time

(i) 0.8
(ii) 0.4
(iii) 0.125
(iv) 1.25

(i) 0.8

## Q9. In an alternating current circuit consisting of elements in series, the current increases on increasing the frequency of supply. Which of the following elements are likely to constitute the circuit?

(i) Only resistor.
(ii) Resistor and an inductor.
(iii) Capacitor and an inductor.
(iv) Only a capacitor.

(iv) Only a capacitor.

## Q10. The electric mains supply in our homes and offices is a voltage that varies like a sine function with time such a voltage is called … A… and the current driven by it in a circuit is called the … B… Here, A and B refer to

(i) DC voltage, AC current
(ii) AC voltage, DC current
(iii) AC voltage, DC voltage
(iv) AC voltage, AC current

(iv) AC voltage, AC current

(i) 256.33 V
(ii) 89.12V
(iii) 0.314 V
(iv) 3.1455 V

(iii) 0.314 V

## Q12. In which of the following circuits the maximum power dissipation is observed?

(i) Pure capacitive circuit
(ii) Pure inductive circuit
(iii) Pure resistive circuit
(iv) None of these

(iii) Pure resistive circuit

## Q13. Power factor of an ac circuit is a measure of:

(i) virtual power
(ii) power lost in the circuit
(iii) mean power
(iv) all the above

(ii) power lost in the circuit

(i) 50 V
(ii) 50√2 V
(iii) 100 V
(iv) zero

(iv) zero

(i) 1/√2A
(ii) √2A
(iii) 2A
(iv) 2√V2A

(i) 1/√2A

## Q16. A.C. power is transmitted from a power house at a high voltage as

(i) the rate of transmission is faster at high voltages
(ii) it is more economical due to less power loss
(iii) power cannot be transmitted at low voltages
(iv) a precaution against theft of transmission lines

(ii) it is more economical due to less power loss

## Q17. Identify the principle behind the working of an a.c. generator.

(i) Eddy currents
(iii) Lenz’s law
(iv) Electromagnetic induction

(iv) Electromagnetic induction

(i) 30°
(ii) 45°
(iii) 60°
(iv) 0°

(iv) 0°

(i) 15 V
(ii) 120 V
(iii) 180 V
(iv) 960 V

(i) 15 V

## Q20. Reciprocal of impedance is

(i) susceptance
(ii) conductance
(iv) transconductance

## Q21. Transformer works on the principle of:

(i) convertor
(ii) invertor
(iii) mutual induction
(iv) self-induction

(iii) mutual induction

## Q22. In which of the following circuits the maximum power dissipation is observed?

(i) Pure capacitive circuit
(ii) Pure inductive circuit
(iii) Pure resistive circuit
(iv) None of these

(iii) Pure resistive circuit

(i) maximum
(ii) minimum
(iii) zero
(iv) infinity

(i) maximum

## Q24. capacitor acts as an infinite resistance for

(i) DC
(ii) AC
(iii) DC as well as AC
(iv) neither AC nor DC

(i) DC

## Q25. For an ideal-step-down transformer, the quantity which is constant for both the coils is

(i) current in the coils
(ii) voltage across the coils
(iii) resistance of coils
(iv) power in the coils

(iv) power in the coils

## Q26. A rejector circuit is:

(i) series resonant circuit
(ii) parallel resonant circuit
(iii) LCR circuit
(iv) None of these

(ii) parallel resonant circuit

## Q27. Which of the following combinations should be selected for better tuning of an LCR circuit used for communication?

(i) R = 20, L= 1.5 H, C = 35 μF.
(ii) R = 25 , L = 2.5 H, C = 45 μF.
(iii) R = 15 , L = 3.5 H, C = 30 μF.
(iv) R = 25 , L = 1.5 H, C = 45 μF.

(iii) R = 15 , L = 3.5 H, C = 30 μF.

## Q28. In pure inductive circuit current

(i) lags behind emf by π/2
(ii) leads the emf by π/2
(iii) lags behind emf by π
(iv) leads the emf by π

(i) lags behind emf by π/2

## Q29. When an AC voltage of 220 V is applied to the capacitor C

(i) the maximum voltage between plates is 220 V.
(ii) the current is in phase with the applied voltage.
(iii) the charge on the plates is not in phase with the applied voltage.
(iv) power delivered to the capacitor is zero.

(iv) power delivered to the capacitor is zero.

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