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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1,052 questions · page 44 of 53
- A. 16 R
- B. 4 R
- C. 2 R
- D. 8 R
Explanation: When a wire is stretched to double its original length, the cross-sectional area is reduced to maintain constant volume.
Correct answer: 4 R- A. 2 Ω
- B. 4 Ω
- C. 1/2 Ω
- D. 1/4 Ω
Explanation: R = pL / A If p (resistivity) and A (area) remain the same, then R ∝ L As L doubles, R will also double. So, R' = 2R R' = 2 Ω
Correct answer: 2 Ω- A. Increases, increases
- B. Decreases, decreases
- C. Increases, decreases
- D. Decreases, increases
Explanation: The resistance of copper decreases when cooled to -150 oC because it is a metal with a positive temperature coefficient of resistance…
Correct answer: Decreases, increases- A. 2A
- B. 2.5 A
- C. 2.2 A
- D. None of these
Explanation: v = ε - l1r → I1R1 = ε - l1r(1.6)(8) = ε - 1.6r → 12.8 = ε - 1.6r → (i)(30)(0.5) = ε - 0.5r → 15 = ε - 0.5r → (ii)Putting eqn i and ii…
Correct answer: 2A- A. lnfinite
- B. Very low
- C. Zero
- D. Very high
Explanation: Internal resistance of ideal current source is infinite as it has zero conductance.
Correct answer: lnfinite- A. 0.04Ω
- B. 0.10Ω
- C. 0.06Ω
- D. 10Ω
Explanation: I=E/R+rWhere:E = EMF of cell=1.5VR = external resistance (ammeter)=R=0.04Ωr = internal resistance of cell=r=?I=Current through ammeter…
Correct answer: 0.06Ω867. If the current in electric bulb decreases by 0.5%, the power in the bulb decreases by approximately:
- A. 1%
- B. 0.5%
- C. 2%
- D. 0.25%
Explanation: %age increases in P = 2 (%age increase in 1) → %age increase in P = 2 (0.5%)=1%
Correct answer: 1%- A. 5 joules
- B. 15 joules
- C. 10 joules
- D. 20 joules
Explanation: To calculate the energy used by the battery, we need to determine the total charge that moves through the battery and apply the formula…
Correct answer: 20 joules- A. 64 W
- B. 100 W
- C. 72W
- D. 90W
Explanation: R = V2/P = (200)2/100 = 400Ω P = V2/R = (160)2/400 = 64 Watt
Correct answer: 64 W- A. 25 W
- B. 60 W
- C. 50 W
- D. 40 W
Explanation: The resistance of high power devices is smaller than the low power ones.
Correct answer: 60 W- A. 16R
- B. 4R
- C. 1/16R
- D. 1/4R
Explanation: Resistance R of a wire is given by the formula R = ρ(L/A), where ρ is resistivity, L is the length, and A is the cross-sectional area.
Correct answer: 1/16R- A. Non-linear
- B. Curve
- C. Linear
- D. Curvilinear
Explanation: The graph shows linear behavior between change in resistance w.r.t temperature below 0oC.
Correct answer: Linear- A. 20 KWh
- B. 12 KWh
- C. 2 KWh
- D. None of the above
Explanation: To determine the electrical consumption, first convert the power from Watts to kilowatts: 400 Watts is equal to 0.4 kW.
Correct answer: 2 KWh- A. Two times
- B. Four times
- C. Eight times
- D. Sixteen times
Explanation: The resistance of a wire is calculated using the formula R = ρ(L/A), where ρ is resistivity, L is length, and A is the cross-sectional…
Correct answer: Sixteen times- A. 180Ω
- B. 225Ω
- C. 342Ω
- D. 317Ω
Explanation: To find the resistance of the tungsten wire at 500 oC, we apply the resistance-temperature relationship formula:R = R0(1 + α(T -…
Correct answer: 342Ω- A. Remain same
- B. Is doubled
- C. Is halved
- D. One fourth
Explanation: Resistivity is a fundamental property of a material, determined by its nature at the atomic level.
Correct answer: Remain same- A. 0.5 x 10^16 amp
- B. 0.5 x 10^12 amp
- C. 2 x 10^12 amp
- D. 2 x 10^-12 amp
Explanation: Charge on one alpha particle is, q = 3.2 × 10¯¹⁹C.Therefore, the total charge passing through the tube in 1 minute is,q = 10000 × 3.2 ×…
Correct answer: 0.5 x 10^16 amp- A. 12
- B. 24
- C. 5
- D. 1100
Explanation: Answer is 12Given:P=500WV=20Vt=24 hoursFormula:1KWh=P×t/1000500W×24hours12000/1000=12 thus 12 is the answer
Correct answer: 12- A. The potential difference across the resistor for each unit of current
- B. The power produced in the circuit for each unit of charge that passes
- C. The work done in the circuit for each unit of charge that passes
- D. The work done in the circuit for each unit of current
Explanation: The electromotive force (e.m.f) of a cell is the total energy supplied by the cell per unit charge, which means it is the work done to…
Correct answer: The work done in the circuit for each unit of charge that passes- A. Diode
- B. Transistor
- C. Generator
- D. Motor
Explanation: Generator is the only suitable device which generates current. Generator is the only suitable device which generates current.
Correct answer: Generator