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.
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- A. Increases with an increase in temperature
- B. Decreases with a decrease in temperature
- C. Decreases with an increase in temperature
- D. None of the above
Explanation: Materials with a negative temperature coefficient exhibit a decrease in resistance as temperature increases.
Correct answer: Decreases with an increase in temperature- A. Increases.
- B. Decreases.
- C. Becomes zero.
- D. Remains unchanged.
Explanation: The resistance of a metallic conductor increases with temperature because the atoms within the conductor vibrate more with added energy…
Correct answer: Increases.- A. The battery's e.m.f and its internal resistance
- B. The battery's e.m.f and the current
- C. The current and the battery's internal resistance
- D. The current and the external resistance
Explanation: d) The current and the external resistance:The current flowing through the external resistor contributes to the voltage drop across the…
Correct answer: The current and the external resistance- A. R > r
- B. R < r
- C. R = r
- D. R = 1/r
Explanation: Maximum Power Transfer occurs when the resistive value of the load is equal in value to that of the voltage source's internal resistance.
Correct answer: R = r- A. Pmax = E2/4r
- B. Pmax = 4rE2
- C. Pmax =VIT
- D. Unlimited
Explanation: Factual recall from PTB. See explanation attached.
Correct answer: Pmax = E2/4r- A. Compare resistances
- B. Determine the current
- C. Determine the charge
- D. Determine the e.m.f
Explanation: The Wheatstone bridge is used for the precise measurement of low resistance.
Correct answer: Compare resistances- A. 10-8 Ωm
- B. 10-10 Ωm
- C. 10-6 Ωm
- D. 102 Ωm
Explanation: a) 10^-8 Ωm:This option suggests a resistivity value of 10^-8 Ωm for copper.
Correct answer: 10-8 Ωm- A. 1 Farad
- B. 10 coulomb
- C. 1 coulomb
- D. 10 ohm
- E. 1 ohm
Explanation: The explanation for this question will be added soon.
Correct answer: 10 ohm- A. 4R
- B. R/4
- C. 8R
- D. 16R
Explanation: If you stretch the wire till its radius is halved the previous value, then its length will increase 4 times to keep the volume constant.
Correct answer: 16R- A. Double
- B. One Forth
- C. One half
- D. 4 times
Explanation: Resistance (R) is directly proportional to the length (L) and inversely proportional to the cross-sectional area (A) of the wire.
Correct answer: 4 times- A. 1 x 10^-7
- B. 2.63 x 10^-8
- C. 19 x 10^-8
- D. 7.85 x 10^-8
Explanation: he resistivity (ρ) of a wire can be calculated using the formula:ρ = (R * A) / Lwhere R is the resistance, A is the cross-sectional area…
Correct answer: 1 x 10^-7- A. Resistance will be doubled and specific resistance will be halved
- B. Resistance will be halved and specific resistance will remain unchanged
- C. Resistance will be halved and specific resistance will be doubled
- D. Resistance and specific resistance will both remian unchanged
Explanation: Option B is correct since we know that, R = pl / A = pl / πr2 R' = p2l / / π(2r2) = R / 2 Specific resistance will remain the same as it…
Correct answer: Resistance will be halved and specific resistance will remain unchanged- A. High voltage
- B. High current
- C. High power
- D. Heating of wires
Explanation: To protect a high-voltage circuit, you need a properly rated fuse. Here are five popular examples for consideration in your next design.
Correct answer: High current- A. 1.0A
- B. 2.5A
- C. 3.0A
- D. 4.0A
Explanation: The explanation for this question will be added soon.
Correct answer: 4.0A- A. Cathode
- B. Grid
- C. Anode Getter
- D. Screen
Explanation: In an electronic device, such as a vacuum tube or an electron tube, the flow of electrons, also known as electron current, is primarily…
Correct answer: Cathode- A. It can measure the internal resistance of a cell
- B. It can measure the e.m.f. of a cell
- C. It is heavy and not portable
- D. It can measure accurately very small PD. of the ord of a few microvolts
Explanation: options A, B, and D would rather be the advantages or uses of potentiometers, hence considering all the options, option C would be the…
Correct answer: It is heavy and not portable- A. Same
- B. Different
- C. Sometimes same, sometimes different
- D. None of them
Explanation: In a series circuit, the current only has one path to flow through and so, the current must be the same at all points so, as to follow the…
Correct answer: Same- A. Increase in temperature
- B. Increase in pressure
- C. Decrease in temperature
- D. Decrease in pressure
Explanation: With the increase in temperature, the random motion of electrons increases.
Correct answer: Increase in temperature- A. E2/4r
- B. E2/2r
- C. E2/5r
- D. E2/3r
Explanation: The Maximum Power Transfer Theorem in electrical circuits states that to transfer the maximum amount of power from a source (like a…
Correct answer: E2/4r- A. Red
- B. Green
- C. Blue
- D. Brown
Explanation: A carbon-composition resistor can have 4 to 6 bands. The assignment of colour according to their bands is shown in the table.The mnemonic…
Correct answer: Green