Alternating Current Class 12 MCQ Questions: Chapter 7 Alternating Current from CBSE Class 12 Physics discusses how it’s quite common to encounter voltages and currents that vary over time. For instance, the electricity supplied to our homes and offices follows a sine wave pattern as time progresses. This type of voltage is referred to as alternating voltage (AC voltage), and the corresponding current that flows through a circuit due to it is called alternating current (AC current). In the present day, a majority of the electronic devices we use are designed to operate with AC voltage. This preference arises mainly because power companies distribute electrical energy predominantly in the form of alternating current. The key advantage of AC voltage over DC voltage lies in its easy and efficient conversion through transformers. Moreover, AC voltage allows economical transmission over long distances. Prepare for the CBSE 12th Physics Board Exam 2024 with these MCQs given with answers.
Alternating Current Class 12 MCQ Questions with Answers
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1 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
2 A.C. power is transmitted from a power house at a high voltage as
(a) the rate of transmission is faster at high voltages
(b) it is more economical due to less power loss
(c) power cannot be transmitted at low voltages
(d) a precaution against theft of transmission lines
Answer: b
3 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
4 Alternating current can not be measured by D.C. ammeter, because
(a) A. C. is virtual
(b) A. C. changes its direction
(c) A. C. can not pass through D.C. ammeter
(d) average value of A. C for complete cycle is zero
Answer: d
5 A transformer works on the principle of
(a) self induction
(b) electrical inertia
(c) mutual induction
(d) magnetic effect of the electrical current
Answer: c
6 What happens to the quality factor of an LCR circuit if the resistance is increased?
- Increases
- Decreases
- Remains the same
- None of the above
Answer: b
7 For an ideal-step-down transformer, the quantity which is constant for both the coils is
(a) current in the coils
(b) voltage across the coils
(c) resistance of coils
(d) power in the coils
Answer: d
8 The core of any transformer is laminated so as to
(a) reduce the energy loss due to eddy currents.
(b) make it light weight.
(c) make it robust and strong.
(d) increase the secondary voltage.
Answer: a
9 The transformation ratio in the step-up transformer is
(a) one
(b) greater than one
(c) less than one
(d) the ratio greater or less than one depends on the other factor
Answer: b
10 The graph between inductive reactance and frequency is
(a) parabola
(b) straight line
(c) hyperbola
(d) an arc of a circle
Answer: b
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