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 10 of 53
- A. 22kW
- B. 44kW
- C. 44watt
- D. 40 kW
Explanation: The formula for electric power is P = IV. P = (200 A) × (220 V) = 44,000 W. Since 1 kW = 1000 W, this is equal to 44 kW.
Correct answer: 44kW- A. 20 KWh
- B. 12 KWh
- C. 2 KWh
- D. None of the above
Explanation: Electrical energy consumption is calculated as Power × Time. First, convert power to kilowatts: 400 W = 0.4 kW.
Correct answer: 2 KWh- A. 250 Ohms
- B. 350 Ohms
- C. 450 Ohms
- D. 484 Ohms
Explanation: In this case, we are given the voltage (V) of the bulb, which is 220 V, and the power P of the bulb, which is 100W.
Correct answer: 484 Ohms- A. Two times
- B. Four times
- C. Eight times
- D. Sixteen times
Explanation: When the diameter is halved, the cross-sectional area becomes one-fourth its original value.
Correct answer: Sixteen times- A. E=I2R
- B. E=IR
- C. E=R/I
- D. E=I/R
Explanation: Ohm's Law describes the relationship between voltage, current, and resistance for a component.
Correct answer: E=IR- A. 180 Ω
- B. 225 Ω
- C. 258 Ω
- D. 317 Ω
Explanation: Using the resistance-temperature relationship R₂ = R₁[1 + α(T₂ - T₁)], we get R500= 133Ω[1 + 0.0045(500 - 150)].
Correct answer: 258 Ω- A. 60J
- B. 1000J
- C. 60kJ
- D. 1kJ
Explanation: Energy is the product of power and time (E = P × t). First, convert time to seconds: 5 minutes = 300 seconds.
Correct answer: 60kJ- A. Remains the same
- B. Is doubled
- C. Is halved
- D. Is one fourth
Explanation: Resistivity is an intrinsic property of a material, meaning it depends on the substance itself, not on its shape or size.
Correct answer: Remains the same- A. 1 x 10^-6
- B. 4 x 10^-7
- C. 3 x 10^-7
- D. 2 x 10^-7
Explanation: l = 50cm = 0.5m and A = 1m × m2 =10-6 m2 . As R=V/i=ρl/A → ρ=VA/li = 4 × 0.52 × 10-6 = 10-6 Ω - m = 1 × 10-6 Ω - m.
Correct answer: 1 x 10^-6- A. 1.5 A
- B. 3 A
- C. 4.5 A
- D. 6 A
Explanation: For resistors in parallel, the equivalent resistance is found using 1/Req = 1/R₁ + 1/R₂ + 1/R₃ = 1/4 + 1/6 + 1/12 = 3/12 + 2/12 + 1/12 =…
Correct answer: 6 A191. How much energy is dissipated as heat in 20 s by a 100 Ω resistor that carries a current of 0.5 A?
- A. 50 J
- B. 100 J
- C. 250 J
- D. 500 J
Explanation: To determine the energy dissipated as heat in a resistor, use the formula: H = I² Rt. For this question, I = 0.5 A, R 100 Ω, and t = 20s.
Correct answer: 500 J- A. 3 W
- B. 6 W
- C. 9 W
- D. 12 W
Explanation: Total current is I=1A in the series circuit. so each resistor gets the same current. power in R₁ is P = I²R = 1²x3 = 3W.
Correct answer: 3 W- A. 2 Ω
- B. 4 Ω
- C. 6 Ω
- D. 8 Ω
Explanation: For a balanced Wheatstone bridge, R₁/R₂ = R₃/R₄. Let the unknown resistance be Rₓ. Using the given values, 2/3 = 4/Rₓ.
Correct answer: 6 Ω- A. 12 V
- B. 10 V
- C. 9.6 V
- D. 8 V
Explanation: Total resistance = Rext + r = 8 + 2 = 10 Ω. Current I = E/(Rext + r) = 12/10 = 1.2 A.
Correct answer: 9.6 V- A. 10 Ω
- B. 20 Ω
- C. 5 Ω
- D. 15 Ω
Explanation: For a square of four identical resistors, the equivalent resistance between opposite corners is Req = R.
Correct answer: 10 Ω- A. 6 W
- B. 12 W
- C. 18 W
- D. 24 W
Explanation: Equivalent resistance for two 3 Ω resistors in parallel is Rₑ𝑞 = (3 × 3)/(3 + 3) = 1.5 Ω. Total current I = V/Rₑ𝑞= 6/1.5 = 4 A.
Correct answer: 24 W- A. 1A
- B. 2A
- C. 1.43 A
- D. 5 A
Explanation: Solving the loop equation 10 - 5I - 2I = 0, we get 10 = 7I, so I = 10/7 ≈ 1.43 A.
Correct answer: 1.43 A- A. R/4
- B. R/2
- C. R
- D. 2R
Explanation: Each part has length L/2, so resistance = R/2. In parallel, 1/Rₑ𝑞 = 1/(R/2) + 1/(R/2) = 2/(R/2) = 4/R. Thus, Rₑ𝑞 = R/4.
Correct answer: R/4- A. 64 W
- B. 80 W
- C. 100 W
- D. 125 W
Explanation: Resistance of the bulb is R = V²/P = 200²/100 = 400 Ω. New power P' = V'²/R = 160²/400 = 64 W.
Correct answer: 64 W- A. 2 A
- B. 3 A
- C. 4 A
- D. 6 A
Explanation: Total resistance = R₁ + R₂ + r = 3 + 6 + 1 = 10 Ω. Current I = E/(Rₜₒₜₐₗ) = 24/10 = 2.4 A.
Correct answer: 2 A