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 43 of 53
- A. 25 cm
- B. 75 cm
- C. 50 cm
- D. 40 cm
Explanation: The potentiometer works by comparing the EMF of a cell with a potential drop across a known length of wire.
Correct answer: 75 cm- A. 9
- B. 17
- C. 36
- D. 34
Explanation: In a parallel circuit, each bulb operates independently with the same voltage across it.
Correct answer: 17- A. 3/2 times the initial value
- B. 3/2 times the value after closing S1
- C. 3/4 times the value after closing S1
- D. 3/4 times the initial value
Explanation: Initially, the ammeter and voltmeter are in series with the battery, measuring the total voltage and current.
Correct answer: 3/2 times the value after closing S1- A. 6V
- B. 5V
- C. 4V
- D. 3V
Explanation: To determine the correct voltmeter reading, we must consider the voltmeter's internal resistance of 6 K Ω.
Correct answer: 5V- A. 5Ω
- B. 2Ω
- C. 7Ω
- D. 1Ω
Explanation: To find the value of R at which the galvanometer reads zero current, one can apply Kirchhoff's laws or the principle of a balanced…
Correct answer: 1Ω- A. 2R
- B. 4R
- C. 8R
- D. 16R
Explanation: When a wire is stretched to double its original length, its cross-sectional area is reduced by half due to the conservation of volume.
Correct answer: 4R- A. 4 ms-1
- B. 0.4 ms-1
- C. 4 cms-1
- D. 0.4 mms-1
Explanation: To determine the drift velocity (vd), use the formula vd = i/(neA), where i is the current, n is the free electron density, e is the…
Correct answer: 0.4 mms-1- A. 3.4 x 10^-6 kg/s
- B. 4.3 x 10^-6 kg/s
- C. 3.4 x 10^-8 kg/s
- D. 4.3 x 10^-8 kg/s
Explanation: The correct answer is 3.4 × 10-8 kg/s. To find the total linear momentum of free electrons, first calculate the current using Ohm's Law: I…
Correct answer: 3.4 x 10^-8 kg/s- A. 1 x 10^-7
- B. 2 x 10^-7
- C. 4 x 10^-7
- D. None of these
Explanation: Resistivity is a fundamental property of a material, unaffected by changes in the physical dimensions of a wire, such as its length or…
Correct answer: 1 x 10^-7- A. 1.875 x 10^20
- B. 6.875 x 10^20
- C. 1.875 x 10^22
- D. 6.875 x 10^22
Explanation: The number of electrons passing through the wire can be determined by using the formula n = It/e, where:I = 500mA = 500 × 10-3 A (since…
Correct answer: 1.875 x 10^20- A. Rs 136
- B. Rs 137
- C. Rs 138
- D. Rs 139
Explanation: New bulbs = 5, Old bulbs = 7: Total wattage of new bulbs = 5 × 50; Total wattage of old bulbs = 7 × 50: Time the new bulbs are kept on = 5…
Correct answer: Rs 138- A. Watt (W)
- B. Kilowatt hour (kWh)
- C. Horse power (hp)
- D. Kilojoule (kJ)
Explanation: The practical unit of power, particularly in contexts like automotive and mechanical engineering, is horsepower (hp).
Correct answer: Horse power (hp)- A. 18 hp
- B. 19 hp
- C. 17 hp
- D. 13500 hp
Explanation: The engine uses a current of 30 A and has a resistance of 15 ohms. To find the power consumed, apply the formula Power = current² ×…
Correct answer: 18 hp- A. 3
- B. 8/9
- C. 1/3
- D. 2
Explanation: To find the ratio of currents in the two wires, we need to use the formula for resistance: R = ρ(L/A), where ρ is resistivity, L is…
Correct answer: 1/3- A. Straight line
- B. Always not straight line
- C. Usually not straight-line
- D. Sometime straight line
Explanation: For non-ohmic devices, graph is not straight line.For instance.look at V-I or I-V graph of a filament or thermistor it is not linear.
Correct answer: Always not straight line- A. Conductance is the reciprocal of resistance and is measured in siemens
- B. Semiconductor diode are ohmic devices
- C. Ohm's law is not applicable at very low and very high temperatures
- D. Ohm's law is not applicable to electron tubes, discharge tubes
Explanation: Semiconductor diode is non-ohmic device.A diode is a two-terminal semiconductor device that acts like a one-way valve for electric…
Correct answer: Semiconductor diode are ohmic devices- A. Energy = (current)2 × resistance × time
- B. Power = (currency)2 × resistance
- C. Potential difference = current × resistance
- D. Resistivity = resistance × area + length
Explanation: Ohm's Law states that the potential difference (voltage) across a conductor is directly proportional to the current flowing through it…
Correct answer: Potential difference = current × resistance- A. 1019
- B. 10-19
- C. 1017
- D. 10-17
Explanation: I = Q / tQ = ne {where n is the number of electrons, e is the charge of an electron}I = ne / t16 x 10-3 = n x 1.6 x 10-19 / 1n = 16 x 10-3…
Correct answer: 1017- A. 4.4 x 10^-6 ohm m
- B. 1.1 x 10^-6 ohm m
- C. 2.2 x 10^-6 ohm m
- D. 0.22 x 10^-6 ohm m
Explanation: The resistance R of a wire is given by the formula R = ρ * (L/A), where ρ is the resistivity, L is the length, and A is the…
Correct answer: 2.2 x 10^-6 ohm m- A. Iron and silver
- B. Platinum and silver
- C. Iron and platinum
- D. silver and gold
Explanation: Temperature coefficient of resistivity of platinum is 0.00520, while the temperature coefficient of resistivity of iron is 0.00520.
Correct answer: Iron and platinum