Free Current Electricity MCQs with Answers
1,052 Current Electricity 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 relates charge flow to potential difference, resistance and resistivity, including how temperature changes a conductor's resistance. Sources with internal resistance have terminal voltage below their emf when delivering current, and maximum power output occurs under a specific load condition rather than at zero resistance.
Last updated
1,052 questions · page 1 of 53
- A. the charge flowing per unit time past a point in the circuit
- B. the energy delivered per unit charge
- C. the resistance per unit length
- D. the potential difference per unit resistance only
Explanation: One ampere is one coulomb per second, so current measures rate of flow of charge.
Correct answer: the charge flowing per unit time past a point in the circuit- A. inversely proportional to the potential difference across it
- B. directly proportional to the potential difference across it
- C. independent of the potential difference
- D. proportional to the square of the potential difference
Explanation: A graph of current against voltage for an ohmic conductor is a straight line through the origin whose gradient is the reciprocal of the…
Correct answer: directly proportional to the potential difference across it- A. proportional to its length and to its cross sectional area
- B. proportional to its length and inversely proportional to its cross sectional area
- C. independent of its dimensions
- D. inversely proportional to its length
Explanation: R equals rho L over A, so a longer wire offers more resistance and a thicker one less, which is why thick cables are used for heavy…
Correct answer: proportional to its length and inversely proportional to its cross sectional area- A. double
- B. half
- C. four times
- D. unchanged
Explanation: Constant volume means doubling the length halves the cross sectional area, and since resistance is proportional to length over area, the…
Correct answer: four times- A. ohm
- B. ohm metre
- C. ohm per metre
- D. volt per ampere
Explanation: Rearranging R equals rho L over A gives rho equal to RA over L, whose units are ohm times metre squared divided by metre, that is ohm…
Correct answer: ohm metre- A. increases, because the lattice ions vibrate more and impede the electrons
- B. decreases, because the electrons move faster
- C. stays constant
- D. falls to zero
Explanation: More vigorous lattice vibrations scatter the drifting electrons more often, shortening the mean free path and raising resistance, which is…
Correct answer: increases, because the lattice ions vibrate more and impede the electrons- A. positive
- B. zero
- C. negative
- D. always exactly one
Explanation: Heating a semiconductor promotes far more electrons across the energy gap than it adds scattering, so the number of charge carriers rises…
Correct answer: negative- A. 10 ohms
- B. 0.97 ohms
- C. 1.03 ohms
- D. 30 ohms
Explanation: Series resistances simply add, giving 10 ohms, and the same current passes through each while the voltages divide in proportion to the…
Correct answer: 10 ohms- A. 12 ohms
- B. 6 ohms
- C. 3 ohms
- D. 0.33 ohms
Explanation: For two equal resistors in parallel the result is simply half of one of them, so 3 ohms.
Correct answer: 3 ohms- A. the same as the potential difference across its terminals when supplying current
- B. the energy supplied by the cell per unit charge driven round the whole circuit
- C. the force exerted on the electrons in newtons
- D. always smaller than the terminal potential difference
Explanation: Despite its name, emf is an energy per unit charge measured in volts, not a force at all.
Correct answer: the energy supplied by the cell per unit charge driven round the whole circuit- A. 12 V
- B. 14 V
- C. 10 V
- D. 2 V
Explanation: The lost volts inside the cell are I times r, that is 2 multiplied by 1, giving 2 V, so the terminal voltage is 12 minus 2, which is 10 V.
Correct answer: 10 V- A. the load resistance is much larger than the internal resistance
- B. the load resistance equals the internal resistance of the source
- C. the load resistance is zero
- D. the internal resistance is zero
Explanation: Matching the load to the internal resistance maximises the power delivered, though the efficiency at that point is only 50 per cent, since…
Correct answer: the load resistance equals the internal resistance of the source- A. I squared R, VI, or V squared over R
- B. IR only
- C. V squared R
- D. I over R
Explanation: All three forms follow from P equals VI combined with Ohm's law, and which one is most convenient depends on what the question gives you.
Correct answer: I squared R, VI, or V squared over R- A. each receives the full mains voltage and can be switched independently
- B. the total resistance is increased
- C. the current through each is the same
- D. less current is drawn overall
Explanation: In parallel every appliance sees the same 220 V and switching one off leaves the others unaffected, whereas a series chain would fail…
Correct answer: each receives the full mains voltage and can be switched independently- A. thick wire of low melting point placed in parallel with the appliance
- B. thin wire of low melting point placed in series with the appliance
- C. high resistance placed in parallel with the supply
- D. device that raises the current to a safe value
Explanation: Being in series, the whole current passes through it, and being thin with a low melting point it melts and breaks the circuit if that…
Correct answer: thin wire of low melting point placed in series with the appliance- A. energy
- B. charge
- C. momentum
- D. resistance
Explanation: The total current entering a junction equals the total leaving, because charge cannot accumulate at a point in a steady circuit.
Correct answer: charge- A. very high resistance
- B. very low resistance, so it hardly alters the current it measures
- C. infinite resistance
- D. the same resistance as the circuit
Explanation: Since the whole current flows through it, any appreciable resistance would reduce that current and falsify the reading, so an ideal…
Correct answer: very low resistance, so it hardly alters the current it measures18. In a metal, the drift velocity of the electrons that make up a current of a few amperes is typically
- A. close to the speed of light
- B. about 1000 m per second
- C. of the order of a millimetre per second
- D. exactly zero
Explanation: Electrons drift extremely slowly because there are so many of them, roughly 10 to the 28 per cubic metre, so a small average velocity…
Correct answer: of the order of a millimetre per second- A. power
- B. energy
- C. current
- D. resistance
Explanation: A kilowatt hour is one kilowatt sustained for one hour, that is 3.6 million joules, and it is the unit an electricity meter records…
Correct answer: energy- A. a higher resistance
- B. a lower resistance and draws more current
- C. the same resistance
- D. a lower current
Explanation: At a fixed voltage, power is V squared over R, so a higher power rating means a lower resistance and therefore a larger current.
Correct answer: a lower resistance and draws more currentCurrent Electricity MCQs: common questions
Are these Current Electricity MCQs free?
Yes. All Current Electricity MCQs from Physics are free on TestUstad, with unlimited attempts and no account needed. Nothing on this page is a sample or a trial.
How many Current Electricity MCQs are on this page?
There are 1,052 Current Electricity MCQs in the Physics bank, shown 20 to a page with the correct answer and an explanation on each.
Does every Current Electricity MCQ have an explanation?
Yes. Each Current Electricity question shows the correct option and a written explanation of why it is correct, so a wrong answer teaches you something rather than just being marked wrong.
Can I take a timed Current Electricity test?
Yes. The practice button on this page starts a free Current Electricity test drawn from the Physics bank. It marks each answer instantly, gives you a score at the end, and can be retaken as many times as you like.