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 9 of 53
- A. 0.04 Ω
- B. 0.10 Ω
- C. 0.06 Ω
- D. 10 Ω
Explanation: The total resistance in the circuit is the sum of the ammeter's resistance (R) and the cell's internal resistance (r).
Correct answer: 0.06 Ω- A. 1%
- B. 0.5%
- C. 2%
- D. 0.25%
Explanation: Power dissipated is given by P = I²R. For small percentage changes, the percentage change in power is approximately twice the percentage…
Correct answer: 1%- A. They have equal currents through them
- B. The resistance of the filaments in both the bulbs is same through them
- C. The resistance of the filament in 40 watt bulb is more than the resistance in 100 watt bulb
- D. The resistance of the filament in 100 watt bulb is more than the resistance in 40 watt bulb
Explanation: Since Power P = V²/R, resistance R = V²/P. Both bulbs are rated for the same voltage (200V).
Correct answer: The resistance of the filament in 40 watt bulb is more than the resistance in 100 watt bulb- A. Halved
- B. Four times
- C. One-fourth
- D. Doubled
Explanation: When the coil is cut in half, its resistance is halved (R' = R/2). Since it's connected to the same voltage source, the power P = V²/R…
Correct answer: Doubled- A. 64 W
- B. 100 W
- C. 72 W
- D. 90 W
Explanation: First, find the bulb's resistance from its rating: R = V²/P = (200V)² / 100W = 400 Ω.
Correct answer: 64 W- A. 200 J
- B. 800 J
- C. 400 J
- D. 40 J
Explanation: The power converted into light is half the total power, so Plight = 0.5 × 40 W = 20 W.
Correct answer: 200 J- A. 200-ohm
- B. 50 ohm
- C. 400 ohm
- D. 5 ohm
Explanation: From the power formula P = V²/R, we can solve for resistance: R = V²/P. R = (200 V)² / 100 W = 40000 / 100 = 400 Ω.
Correct answer: 400 ohm- A. 25 W
- B. 60 W
- C. 50 W
- D. 40 W
Explanation: All bulbs are designed for the same voltage (like in a standard household), and resistance is R = V²/P.
Correct answer: 60 W- A. Ω-m²
- B. (Ω-m)-1
- C. Ω-m
- D. (Ω-m)-2
Explanation: Resistivity (ρ) is defined by the formula R = ρL/A. Rearranging for ρ gives ρ = RA/L.
Correct answer: Ω-m- A. 120 A
- B. 120 x 10^3A
- C. 120 x 10^-3 A
- D. None
Explanation: The current (I) can be calculated using the equation V = IR(120) = (1000)(I)120/1000 = II = 120 times 10-3 A.
Correct answer: 120 x 10^-3 A- A. 45 W
- B. 90 W
- C. 290 W
- D. 360 W
Explanation: First, convert the current to Amperes: I = 500 mA = 0.5 A. Use the power formula P = I²R. P = 0.5 A² × 180 Ω = 0.25 × 180 = 45 W.
Correct answer: 45 W- A. 5V
- B. 1.2V
- C. 0.9V
- D. 0.6V
Explanation: First, find the total current in the circuit: I = E / (Rext + rint) = 1.5V / (3.0Ω + 2.0Ω) = 0.3 A.
Correct answer: 0.9V- A. 22 kW
- B. 22 W
- C. 2.2 kW
- D. 2.2 W
Explanation: The rate of energy transfer is power (P). The formula for electrical power is P = VI. P = (220 V) × (0.1 A) = 22 W.
Correct answer: 22 W- A. 4R
- B. 3R
- C. 2R
- D. R
Explanation: The resistance of a wire is given by R∝L/A, and the cross-sectional area is proportional to the square of the diameter, A∝d².
Correct answer: 2R- A. 16R
- B. 4R
- C. 1/16 R
- D. 1/4R
Explanation: Assuming the volume of the wire is conserved during compression, if the radius doubles (r' = 2r), the area becomes 4 times larger (A' =…
Correct answer: 1/16 R- A. Filament bulb
- B. Semiconductor diode
- C. Transistor
- D. Copper wire
Explanation: An Ohmic device has a constant resistance, meaning its V-I graph is a straight line.
Correct answer: Copper wire- A. Non-linear
- B. Curve
- C. Linear
- D. Curvilinear
Explanation: For many metallic conductors, the relationship between resistance and temperature is approximately linear over a wide range, including…
Correct answer: Linear- A. 11Ω
- B. 121Ω
- C. 20Ω
- D. 200Ω
Explanation: From the power formula P = V²/R, we can rearrange to find the resistance: R = V²/P. R = (110 V)² / 100 W = 12100 / 100 = 121 Ω.
Correct answer: 121Ω- A. Double
- B. Four times
- C. One half
- D. One fourth
Explanation: Resistance is given by R = ρL/A. The new resistance R' will be R' = ρ(2L) / (A/2) = 4(ρL/A) = 4R. The resistance becomes four times larger.
Correct answer: Four times- A. Temperature and nature of material
- B. Length
- C. Area
- D. All
Explanation: Conductivity, like its inverse resistivity, is an intrinsic property of a material.
Correct answer: Temperature and nature of material