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Access the latest Class 12 Physics MCQs for Chapter 7 on Alternating Current, complete with answers. These MCQs are tailored to the latest exam pattern, helping students enhance their critical thinking skills and achieve high scores in board exams.
CBSE Class 12 Alternating Current MCQs
Q. What is the frequency of the AC mains in India?
a) 60 Hz
b) 50 Hz
c) 40 Hz
d) 30 Hz
Answer: b) 50 Hz
Q. An alternating current can be produced by:
a) Choke Coil
b) Dynamo
c) Electric Motor
d) Transformer
Answer: b) Dynamo
Q. Which of the following can measure an alternating current?
a) Voltmeter
b) Ammeter
c) Suspended coil galvanometer
d) Moving coil galvanometer
Answer: b) Ammeter
Also Read: Electric Charges and Fields
Q. Which of the following circuits exhibits maximum power dissipation?
a) Pure Inductive Circuit
b) Pure Capacitive Circuit
c) Pure Resistive Circuit
d) None of the above
Answer: c) Pure Resistive Circuit
Q. What happens to the inductive reactance when the frequency of the AC supply is increased?
a) Increases
b) Decreases
c) Remains the same
d) Becomes zero
Answer: a) Increases
Q. The phase difference between current and voltage in a pure resistive circuit is:
a) π/2
b) 0
c) π
d) π/4
Answer: b) 0
Also Read: Current Electricity
Q. In a pure capacitive circuit, if the frequency of the AC source is doubled, then its capacitive reactance will be:
a) Remains the same
b) Doubled
c) Halved
d) Zero
Answer: c) Halved
Q. In an AC circuit, V and I are given by V = 100 sin (100t) volt and I = 100 sin (100t + π/3) mA. The power dissipated in the circuit is:
a) 104 W
b) 10 W
c) 2.5 W
d) 5 W
Answer: c) 2.5 W
Q. In a series LCR circuit, the voltage across each of the components L, C, and R is 50 V. The voltage across the LC combination will be:
a) 50 V
b) 50√2 V
c) 100 V
d) Zero
Answer: d) Zero
Q. The power factor of an AC circuit is:
a) The ratio of real power to apparent power
b) The ratio of apparent power to real power
c) Always greater than 1
d) Always less than 1
Answer: a) The ratio of real power to apparent power
Read More: Communication System
Q. A transformer works on the principle of:
a) Mutual induction
b) Self-induction
c) Electromagnetic induction
d) All of the above
Answer: a) Mutual induction
Q. In an AC circuit containing a pure inductance, the current:
a) Leads the voltage by π/2
b) Lags the voltage by π/2
c) Is in phase with the voltage
d) Leads the voltage by π
Answer: b) Lags the voltage by π/2
Q. The average power dissipation in a pure inductor or capacitor is:
a) Maximum
b) Minimum
c) Zero
d) Infinite
Answer: c) Zero
Q. For maximum efficiency, the power factor of a circuit should be:
a) 0
b) 1
c) Between 0 and 1
d) Greater than 1
Answer: b) 1
Read More: Wave Optics
Q. The impedance of an LCR series circuit is minimum at:
a) Resonance frequency
b) Zero frequency
c) Infinite frequency
d) Half of the resonance frequency
Answer: a) Resonance frequency
Q. In an LCR circuit, at resonance, the current:
a) Is maximum
b) Is minimum
c) Is zero
d) Depends on the values of L, C, and R
Answer: a) Is maximum
Q. The RMS value of AC is equal to the DC current that produces the same:
a) Voltage
b) Heat
c) Current
d) Power
Answer: d) Power
Q. In a transformer, the primary and secondary coils are:
a) Always connected in series
b) Always connected in parallel
c) Inductively coupled
d) Capacitively coupled
Answer: c) Inductively coupled
Q. The ratio of the number of turns in the primary coil to the number of turns in the secondary coil of a transformer is 10:1. If the primary voltage is 220 V, the secondary voltage is:
a) 22 V
b) 2200 V
c) 110 V
d) 440 V
Answer: a) 22 V
Q. The power factor of an RLC circuit at resonance is:
a) 0
b) 1
c) Between 0 and 1
d) Greater than 1
Answer: b) 1
Q. In an AC circuit, the voltage and current are given by V = V₀ sin(ωt) and I = I₀ sin(ωt + π/2). The power factor of the circuit is:
a) 0
b) 1
c) 0.5
d) -1
Answer: a) 0
Q. A choke coil is used in AC circuits to:
a) Increase current
b) Decrease current
c) Increase voltage
d) Decrease voltage
Answer: b) Decrease current
Q. A capacitor blocks:
a) AC
b) DC
c) Both AC and DC
d) Neither AC nor DC
Answer: b) DC
Q. In an AC circuit, the effective value of current is:
a) RMS value
b) Average value
c) Peak value
d) Instantaneous value
Answer: a) RMS value
Q. In a series LCR circuit, if the capacitive reactance is equal to the inductive reactance, the circuit:
a) Is purely resistive
b) Is purely inductive
c) Is purely capacitive
d) Has maximum impedance
Answer: a) Is purely resistive
Q. The bandwidth of a series resonant circuit is:
a) Independent of resonance frequency
b) Directly proportional to resonance frequency
c) Inversely proportional to resonance frequency
d) Independent of circuit elements
Answer: b) Directly proportional to resonance frequency
More Resources for Class 12
- NCERT Solutions Class 12
- NCERT Solutions Class 12 Maths
- NCERT Solutions Class 12 Physics
- NCERT Solutions Class 12 Chemistry
- NCERT Solutions Class 12 Biology
Q. In a parallel LC circuit, the impedance at resonance is:
a) Zero
b) Maximum
c) Minimum
d) Infinite
Answer: d) Infinite
Q. In a series resonant circuit, the voltage across the capacitor is 100 V, and across the inductor is also 100 V. The voltage across the resistor is 40 V. The supply voltage is:
a) 140 V
b) 200 V
c) 40 V
d) 240 V
Answer: c) 40 V
Q. A transformer has 50 turns in the primary coil and 100 turns in the secondary coil. If the primary voltage is 220 V, the secondary voltage is:
a) 110 V
b) 440 V
c) 220 V
d) 330 V
Answer: b) 440 V
