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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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Steady CurrentResistance and ResistivityTemperature Coefficient of ResistivityInternal Resistance of SourcesMaximum Power Output
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1,052 questions · page 7 of 53

121. During electrolysis, positive ions migrate towards the cathode (negative electrode) and get reduced. In the case of CuSO4, Cu ions get reduced and deposited onto the cathode.Incorrect options: (a) The anode is where oxidation occurs, not deposition of copper. (c) Copper is specifically deposited at the cathode during the electrolysis of CuSO4. (d) Copper is indeed deposited during the electrolysis process.

  • A. ink pump
  • B. deflecting plates
  • C. charging electrodes
  • D. gutter

Explanation: In inkjet printers, the computer sends instructions to the deflecting plates, which precisely control the direction of the ink droplets as…

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Correct answer: deflecting plates

122. Four resistors A, B, C, and D form a Wheatstone bridge. The bridge is balanced when C = 100 Ω. If A and B are interchanged, the bridge balances for C = 121 Ω. The value of D is

  • A. 10Ώ
  • B. 100Ώ
  • C. 110Ώ
  • D. 120Ώ

Explanation: In a balanced Wheatstone bridge, the voltage across the resistors C and D is zero.

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Correct answer: 110Ώ

123. A wire of uniform cross section A , length 1 and resistance R is cut into two equal pieces. The resistivity of each piece will be

  • A. the same
  • B. one fourth
  • C. double
  • D. one half

Explanation: Resistivity is a fundamental property of a material that describes its opposition to the flow of electric current.

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Correct answer: the same

124. the metalic wires are lying parallel. if the current in these wires be flowing in same direction, the wires will

  • A. attract each other
  • B. repel each other
  • C. have no force of attraction or repulsion
  • D. remain stationary

Explanation: When two parallel wires carry current in the same direction, they attract each other (a).

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Correct answer: attract each other

125. the color coded resistances are made by

  • A. high grade silver rods
  • B. high grade ceramic rods
  • C. high grade copper rods
  • D. high grade iron rods

Explanation: The color-coded resistors are typically made using high-grade ceramic rods

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Correct answer: high grade ceramic rods

126. a wire of radius r has resistances R. if is stretched to a wire of r/2 radius, then the resistance becomes

  • A. 2R
  • B. 4R
  • C. 16R
  • D. Zero

Explanation: Resistance of a wire is given by R = ρL/AWhere, ρ is resistivity of material of wire (constant)L is length of wireA is cross-sectional…

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Correct answer: 4R

127. a uniform resistance wire of length L and diameter d has a resistance R. another wire of same material has length, 4Lnand diameter 2d, the resistance will be

  • A. 2R
  • B. R
  • C. R/2
  • D. R/4

Explanation: We can find the new resistance of the second wire by considering the relationship between resistance, length, and cross-sectional area in…

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Correct answer: R

128. Two metallic conductors have the same value of resistivity. These conductors can be differentiated from the values of their

  • A. Temperature coefficient
  • B. Resistance
  • C. Conductance
  • D. Conductivity

Explanation: Even if two metallic conductors have the same resistivity, their resistances may differ depending on their dimensions (length…

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Correct answer: Resistance

129. Two metallic wires are lying parallel. If the current in these wires be flowing in the same direction, the wires will:

  • A. Attract each other
  • B. Repel each other
  • C. Have no force of attraction or repulsion
  • D. Remain stationary

Explanation: Parallel currents in the same direction produce magnetic fields that repel each other, leading to a repulsive force between the wires.

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Correct answer: Repel each other

130. Which material is commonly used as an electrical conductor in daily use?

  • A. Copper
  • B. Aluminium
  • C. Steel
  • D. Nickle

Explanation: Copper is the most common material used as an electrical conductor in daily use.

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Correct answer: Copper

131. In modern day electrical arrangements, which of the following is connected in series with the others?

  • A. fan
  • B. Bulb
  • C. Tube Lights
  • D. None of these

Explanation: In modern electrical arrangements, appliances and devices are typically connected in parallel, not in series.

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Correct answer: None of these

132. Unit of energy density of electric field is:

  • A. JC-1
  • B. Jm-3
  • C. JV-1
  • D. JF-3

Explanation: Energy density is defined as the amount of energy stored per unit volume.

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Correct answer: Jm-3

133. Two heaters A and B are connected in parallel across the supply voltage. Heater A produces 500 kJ in 20 minutes and B produces 1000 kJ in 10 minutes. The resistance of A is 100 Ω. If the same heaters are connected in series across the same voltage, the heat produced in 5 minutes will be:

  • A. 200 kJ
  • B. 100 kJ
  • C. 50 kJ
  • D. 10 kJ

Explanation: First, calculate the power and resistance of each heater, then find the total power when they are in series across the same voltage.

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Correct answer: 100 kJ

134. Basically a potentiometer is a device for:

  • A. Comparing two voltages
  • B. Measuring a current
  • C. Comparing two currents
  • D. Measuring a voltage

Explanation: A potentiometer works on the principle of null deflection and is mainly used to compare an unknown voltage with a known standard voltage…

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Correct answer: Comparing two voltages

135. An electric heater is designed to operate in a 100 V main with a power output of 1000 W. When it is connected to a 25 V source, the power output is:

  • A. 40 W
  • B. 100 W
  • C. 62.5 W
  • D. 250 W

Explanation: Calculate the heater's resistance using its values: R = V²/P = (100V)² / 1000W = 10 Ω.

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Correct answer: 62.5 W

136. A reasonable cause for the increase in resistivity of conductors with rising temperature is:

  • A. The mass of the electron changes with temperature
  • B. The charge on each electron changes with temperature
  • C. The electron density changes with temperature
  • D. The time between collisions changes with temperature

Explanation: As the temperature increases in a conductor, the lattice ions vibrate more vigorously.

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Correct answer: The time between collisions changes with temperature

137. The e.m.f of the driver cell in a potentiometer circuit is 10 V. The length of the potentiometer wire is 1 m and its resistance is 9 Ω. A cell of e.m.f 5 V is balanced on the 5/9 m length of the wire. The internal resistance of the driver cell is:

  • A. 1 Ω
  • B. 0.1 Ω
  • C. 2 Ω
  • D. 0.5 Ω

Explanation: The balancing condition gives the potential drop across the wire length. The current in the primary circuit is I = E / (R + r).

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Correct answer: 1 Ω

138. A dry cell delivering 2 A has a terminal voltage of 1.41V. What is the internal resistance of the cell if its open-circuit voltage is 1.59 V?

  • A. 5.09 Ω
  • B. 6.09 Ω
  • C. 7.09 Ω
  • D. 0.09 Ω

Explanation: The relationship between EMF (E), terminal voltage (V), current (I), and internal resistance (r) is V = E - Ir.

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Correct answer: 0.09 Ω

139. The current through a conductor is directly proportional to the potential difference between the ends of the conductor, provided that physical conditions remain the same. This is:

  • A. Laplace's Law
  • B. Ohm's Law
  • C. Coulomb's Law
  • D. Charles's Law

Explanation: This statement defines Ohm's Law, which says that current is directly proportional to potential difference when temperature and other…

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Correct answer: Ohm's Law

140. When cells are arranged in parallel:

  • A. The current capacity decreases
  • B. The current capacity increases
  • C. The e.m.f increases
  • D. The e.m.f decreases

Explanation: Connecting cells in parallel keeps the total EMF the same as a single cell but reduces the total internal resistance.

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Correct answer: The current capacity increases
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