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Free Steady Current MCQs with Answers

87 Steady 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.

Steady current is the continuous flow of charge at a constant rate through a conductor. The topic covers current, charge, potential difference, resistance, Ohm's law, resistivity and electrical power, along with series and parallel circuits, while distinguishing conventional current direction from electron motion.

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87 questions · page 5 of 5

81. For ohmic substance, the electron drift velocity is proportional to:

  • A. Cross sectional of the sample
  • B. The length of sample
  • C. The mass of an electron
  • D. The electric field in the sample

Explanation: Drift velocity is proportional to current. In a resistive material, it is also proportional to the magnitude of an external electric…

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Correct answer: The electric field in the sample

82. The sum of the e.m.f and potential differences around a closed circuit is zero is a consequence of:

  • A. Ohm's law
  • B. Newton's 2nd law
  • C. Conservation of energy
  • D. Conservation of charge

Explanation: The second law of Kirchoff states that around any closed loop in a circuit, the sum of potential differences and emf is zero.

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Correct answer: Conservation of energy

83. Four wires meet at a junction. The first carries 4A in to the junction, the second carries 5A out of the junction, and third carries 2A out of the junction. The fourth carries:

  • A. 7A out of the junction
  • B. 7A into the junction
  • C. 3A out of the junction
  • D. 3A in to the junction

Explanation: D. Kirchoff's Junction rule states that the total current into a junction is equal to that out of the junction hence 3+4in = 5+2out

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Correct answer: 3A in to the junction

84. A 0.01A moving coil Galvanometer of 5 Ω resistance can be converted into a 0.2A ammeter by a resistance R with the Galvanometer when r is:

  • A. 0.25 Ω in parallel
  • B. 0.25 Ω in series
  • C. 0.50 Ω in parallel
  • D. 0.50 Ω in series

Explanation: A galvanometer is converted into an ammeter by connecting a low resistance in parallel with the galvanometer.

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Correct answer: 0.25 Ω in parallel

85. A total charge of 100C flows through a 12W bulb in a time of 50 second. What is the potential difference across the bulb during this time?

  • A. 0.12V
  • B. 2.0V
  • C. 6.0V
  • D. 24V

Explanation: The correct answer is 6.0V, determined by using the formula P = VI, where P is power, V is voltage, and I is current.

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Correct answer: 6.0V

86. Kirchofrs current law (KM.) Is based upon law Of conservation of:

  • A. Mass
  • B. Energy
  • C. Momentum
  • D. Charge

Explanation: Kirchhoff's current law (KCL) is based upon the law of conservation of charge.

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Correct answer: Charge

87. A certain X-ray tube requires a current of 5mA at a voltage of 60kv. The rate of energy dissipation (in watts) is:

  • A. 560
  • B. 300
  • C. 200
  • D. 800

Explanation: To calculate the rate of energy dissipation (power) in an X-ray tube, we use the formula P = IV, where P is the power in watts, I is the…

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Correct answer: 300
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