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Free Alternating Current MCQs with Answers

592 Alternating Current MCQs from Physics, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.

Alternating current varies periodically, so phase relationships become essential when current passes through a resistor, capacitor or inductor. The chapter distinguishes resistance from capacitive and inductive reactance, explains phase lead and lag, and connects changing electric and magnetic fields with the production and properties of electromagnetic waves.

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Phase of Alternating CurrentAC Through Resistor, Capacitor and InductorElectromagnetic Waves
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592 questions · page 25 of 30

481. Spot the error. Mahira is angry, and who wants to make Shahrukh apologize for his rude attitude.

  • A. who
  • B. to
  • C. apologize
  • D. his

Explanation: The error in the sentence is in option (A) "who." It should be corrected to "she" to properly form a grammatically correct sentence.

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Correct answer: who

482. Spot the error. Baba Bullah Shah is considered Shakespeare of Punjabi Literature because of the deep philosophy expressed in his poetry.

  • A. is
  • B. Shakespeare
  • C. because
  • D. the

Explanation: This is incorrect because it lacks the definite article "the" before "Shakespeare." The sentence needs to specify that Baba Bullah Shah is…

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Correct answer: Shakespeare

483. Spot the error. It will pass to the west of Giggles wick and continue the north towards Ingleton.

  • A. will pass
  • B. the west
  • C. the north
  • D. towards

Explanation: This is incorrect. It should be "continue north" without "the." The correct sentence should be: "It will pass to the west of Giggleswick…

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Correct answer: the north

484. Each sentence below has a blank indicating that something has been omitted. Choose the word that best fits in with the meaning of the sentence as a whole.Since the people of the Subcontinent were _ under English régime, many headed toward the Japanese side during the second world war.

  • A. Employed
  • B. Exiled
  • C. Edified
  • D. Manipulated

Explanation: The best word to fit in the blank is "manipulated."So the completed sentence is:"Since the people of the Subcontinent were manipulated…

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Correct answer: Manipulated

485. Directions: In the following question, a number sequence is given with one term missing. Choose the correct term that will continue the same pattern and replace the question mark in the given sequence.4,6,12,14,28,30,?

  • A. 32
  • B. 60
  • C. 62
  • D. 64

Explanation: The sequence alternates between adding 2 and multiplying by 2, starting with addition: 4 + 2 = 66 x 2 = 1212 + 2 = 1414 x 2 = 2828 + 2 =…

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Correct answer: 60

486. In the following question, two statements numbered I and II are given. There may be cause and effect relationship between the two statements. These two statements may be the effect of the same cause or independent causes. These statements may be independent causes without saving any relationship. Read both the statements in question and mark your answer as:A. If statement I is the cause and statement II is its effect;B. If statement II is the cause and statement, I is its effect;C. If both the statements I and II are independent causes;D. If both the statements I and II are effects of independent causes;E. If both the statements I and II are effects of some common causes;I. There was a huge rush of people to the Passport Office last Friday.II. The authorities had decided to close it down for a month and relocate elsewhere.

  • A. If statement I is the cause and statement II is its effect;
  • B. If statement II is the cause and statement I is its effect;
  • C. If both the statements I and II are independent causes;
  • D. If both the statements I and II are effects of independent causes;
  • E. If both the statements I and II are effects of some common cause;

Explanation: Statement II is the cause and statement I is its effect. The announcement of the Passport Office's closure for a month likely caused a…

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Correct answer: If statement II is the cause and statement I is its effect;

487. In this question, a statement is given followed by two courses of action numbered I and II. It is required to grasp the statement, analyze the problem or policy it mentions and then decide which of the courses of action logically follow / most appropriate.Statement:The committee has criticized the institute for its failure to implement a dozen of regular programmes despite an increase in the staff strength and not drawing up a firm action plan for studies and research.Courses of action:I) The broad objectives of the Institute should be redefined to implement a practical action plan.II) The Institute should give a report on reasons for not having implemented the planned programmes.

  • A. If only I follows
  • B. If only II follows
  • C. If either I or II follows
  • D. If neither I nor II follows
  • E. If both I and II follow

Explanation: Both courses of action are necessary: redefining objectives and implementing a practical plan addresses the committee's concerns, while…

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Correct answer: If both I and II follow

488. 1) A choke is used for resistance in _

  • A. . dc circuit
  • B. ac circuit
  • C. both ac and dc
  • D. full wave rectifier circuit

Explanation: Answer: b. ac circuitExplanation: A choke is an inductor that is primarily used to provide impedance to alternating current (ac) in a…

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Correct answer: ac circuit

489. At resonance, the value of the power factor in an L-C-R series circuit is

  • A. Zero
  • B. 1/2
  • C. 1
  • D. Not definite

Explanation: Explanation: At resonance in an L-C-R series circuit, the impedance becomes purely resistive, and the power factor is maximum.

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Correct answer: 1

490. An A.C. series circuit contains 4-ohm resistance and 3-ohm inductive reactance. The impedance of the circuit is:

  • A. 1 ohm
  • B. 5 ohm
  • C. 7 ohm
  • D. ( frac{7}{sqrt{2}} ) ohm

Explanation: Answer: c. 7 ohmExplanation: In an A.C. series circuit, the impedance ((Z)) is given by the formula (sqrt{(R^2 + X_L^2)}), where (R) is…

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Correct answer: 7 ohm

491. The phase angle between the voltage and the current in an AC circuit consisting of a resistance is:

  • A. zero
  • B. 45 degrees
  • C. 90 degrees
  • D. 180 degrees

Explanation: Answer: a. zeroExplanation: In an AC circuit containing only resistance, the voltage and current are in phase with each other.

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Correct answer: zero

492. Radio receivers are usually tuned by adjusting the capacitor of an LC circuit. If ( C = C_i ) for a frequency of 600 kHz, then for a frequency of 1200 kHz, one must adjust ( C ) to

  • A. ( C_i/2 )
  • B. ( C_i/4 )
  • C. ( 2C_i )
  • D. ( 4C_i )

Explanation: Answer: (b) ( C_i/4 )Explanation: The resonant frequency (( f )) of an LC circuit is given by the formula ( f = frac{1}{2pisqrt{LC}} )…

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Correct answer: ( C_i/4 )

493. Average value of current and voltage over a cycle of AC is:

  • A. positive
  • B. negative
  • C. both
  • D. zero

Explanation: In an alternating current (AC) circuit, the current and voltage vary sinusoidally over time.

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Correct answer: both

494. A changing magnetic flux produces around itself as induced:

  • A. magnetic field
  • B. electric field
  • C. electromagnetic force
  • D. artificial gravitational field

Explanation: According to Faraday's law of electromagnetic induction, a changing magnetic flux induces an electromotive force (EMF) or voltage in a…

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Correct answer: electric field

495. The direction of propagation of an electromagnetic wave is:

  • A. Perpendicular to electric field
  • B. Perpendicular to both electric and magnetic field
  • C. Perpendicular to magnetic field
  • D. Parallel to electric and magnetic field

Explanation: The correct option is (b) because electromagnetic waves consist of both electric and magnetic fields oscillating perpendicular to each…

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Correct answer: Perpendicular to both electric and magnetic field

496. An electromagnetic wave consists of:

  • A. Electric and magnetic fields moving parallel to each other
  • B. Magnetic field moving with the velocity of light in space
  • C. Electric field moving with the velocity of light
  • D. Electric and magnetic fields moving perpendicular to each other

Explanation: An electromagnetic wave is a transverse wave, meaning that the electric and magnetic fields oscillate perpendicular to the direction of…

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Correct answer: Electric and magnetic fields moving perpendicular to each other

497. Electromagnetic waves transport:

  • A. Energy
  • B. Mass
  • C. Heat
  • D. None

Explanation: Electromagnetic waves, including light, are a form of energy transfer. They do not carry mass; instead, they transport energy through…

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Correct answer: Energy

498. ) Waves emitted from the antenna are:

  • A. Sound waves
  • B. Electromagnetic waves
  • C. Radio waves
  • D. Modulated waves

Explanation: When waves are emitted from an antenna, they are typically radio waves.

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Correct answer: Radio waves

499. If the capacitance of an L-C circuit is made four times, then the frequency of the circuit becomes:

  • A. Twice
  • B. One-half
  • C. Four times
  • D. None

Explanation: The resonant frequency ((f_0)) of a series L-C circuit is inversely proportional to the square root of the product of inductance (L) and…

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Correct answer: One-half

500. To find the r.m.s value of an alternating current mathematically, we need to have:

  • A. Mean value of 12
  • B. Square root of mean value of 12
  • C. Square root of 12
  • D. Square of 1/2

Explanation: The Root Mean Square (R.M.S) value of an alternating current is calculated using the following formula:[ I_{{rms}} = sqrt{frac{1}{T}…

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Correct answer: Square root of mean value of 12
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