Bihar Board - Class 12 Physics - Chapter 7: Alternating Current Multiple Choice Questions (MCQs)
For Class 12 Bihar Board, the chapter Alternating Current in Physics define the generation, characteristics, and applications of AC, along with concepts like reactance, impedance, and resonance in LCR circuits. On Vidyakul, you can find multiple-choice questions that help in mastering these topics and preparing effectively for exams.
Multiple Choice Question
1.Energy dissipated in LCR circuit in :
(A) L only
(B) C only
(C) R only
(D) All of the above
Answer: (C) R only
2. In a LCR circuit capacitance is changed from C to 5C for the resonant frequency to remain unchanged, the inductance should be changed from L to value:
(A) 4 L
(B) 2 L
(C) L/5
(D) L/4
Answer: (C) L/5
3. 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?
(A) Inductor and capacitor.
(B) Resistor and inductor.
(C) Resistor and capacitor.
(D) None.
Answer: (A) Inductor and capacitor.
4. Alternating currents can be produced by a
(A) dynamo
(B) choke coil
(C) transformer
(D) electric motor
Answer: (A) dynamo
5. In a pure capacitive circuit if the frequency of ac source is doubled, then its capacitive reactance will be
(A) remains same
(B) doubled
(C) halved
(D) zero
Answer: (C) halved
6. 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?
(A) Only resistor
(B) Resistor and inductor
(C) Resistor and capacitor
(D) Only inductor
Answer: (C) Resistor and capacitor
7. The dimensional formula of L/R is similar to that of:
(A) frequency
(B) time
(C) length
(D) none of these
Answer: (B) time
8. A series AC circuit connected to 220 V, 50 Hz supply consists of a resistance of 100 Ω, inductive reactance of 10 Ω and a capacitive reactance of 10 Ω. Calculate the power factor of the circuit.
(A) 1.0
(B) 0.4
(C) 0.125
(D) 1.25
Answer: (A) 1.0
9. 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?
(A) Only resistor.
(B) Resistor and an inductor.
(C) Capacitor and an inductor.
(D) Only a capacitor.
Answer: (D) Only a capacitor.
10. 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
(A) DC voltage, AC current
(B) AC voltage, DC current
(C) AC voltage, DC voltage
(D) AC voltage, AC current
Answer: (iv) AC voltage, AC current
11. What is the power factor of a alternating current circuit?
(A) (apparent power) / (active power)
(B) (active power) / (reactive power)
(C) (active power) / (apparent power)
(D)(reactive power) / (apparent power)
Answer: (C) (active power) / (apparent power)
12. In which of the following circuits the maximum power dissipation is observed?
(A) Pure capacitive circuit
(B) Pure inductive circuit
(C) Pure resistive circuit
(D) None of these
Answer: (C) Pure resistive circuit
13. 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
Answer: (B) power lost in the circuit
