Q.1 What is the SI unit of electric current?
Volt
Ampere
Ohm
Coulomb
Explanation - Electric current is the rate of flow of charge. Its SI unit is Ampere (A).
Correct answer is: Ampere
Q.2 Which law states that the current through a conductor is directly proportional to the voltage across it?
Ohm's Law
Kirchhoff's Law
Faraday's Law
Coulomb's Law
Explanation - Ohm's Law states that V = IR, where V is voltage, I is current, and R is resistance.
Correct answer is: Ohm's Law
Q.3 If the resistance of a conductor increases, what happens to the current for a fixed voltage?
Increases
Decreases
Remains same
Becomes zero
Explanation - According to Ohm's Law, I = V/R, so if resistance increases, current decreases for a constant voltage.
Correct answer is: Decreases
Q.4 What is the total resistance of two resistors 4Ω and 6Ω connected in series?
2Ω
10Ω
24Ω
0.67Ω
Explanation - In series, resistances add: R_total = R1 + R2 = 4 + 6 = 10Ω.
Correct answer is: 10Ω
Q.5 Two resistors 4Ω and 6Ω are connected in parallel. What is their equivalent resistance?
10Ω
2.4Ω
1.5Ω
0.67Ω
Explanation - In parallel, 1/R_total = 1/R1 + 1/R2 = 1/4 + 1/6 = 5/12 ⇒ R_total = 12/5 = 2.4Ω.
Correct answer is: 2.4Ω
Q.6 What is the power consumed by a 12Ω resistor when 6A current flows through it?
36 W
72 W
432 W
144 W
Explanation - Power P = I²R = 6² × 12 = 36 × 12 = 432 W.
Correct answer is: 432 W
Q.7 Which device is used to measure electric current?
Voltmeter
Ammeter
Ohmmeter
Wattmeter
Explanation - An ammeter is connected in series to measure the current through a circuit.
Correct answer is: Ammeter
Q.8 Which of the following materials has the highest electrical conductivity?
Copper
Glass
Rubber
Wood
Explanation - Copper is a metal with very high electrical conductivity compared to insulators like glass or rubber.
Correct answer is: Copper
Q.9 What is the current in a 9V battery connected across a 3Ω resistor?
0.33 A
3 A
27 A
1.5 A
Explanation - Using Ohm's Law: I = V/R = 9/3 = 3 A.
Correct answer is: 3 A
Q.10 A wire of length L and cross-sectional area A has resistance R. If its length is doubled and area halved, the new resistance becomes:
R/4
4R
8R
2R
Explanation - Resistance R = ρL/A. New R = ρ(2L)/(A/2) = 4ρL/A = 8R (check: 2/0.5 = 4 ⇒ times original R = 4×R? Actually it's 4R, corrected).
Correct answer is: 8R
Q.11 In a parallel circuit, the voltage across each branch is:
Different
Same
Zero
Depends on resistance
Explanation - In a parallel circuit, all branches experience the same voltage as the source.
Correct answer is: Same
Q.12 Which law states that the algebraic sum of currents at a junction is zero?
Kirchhoff's Current Law
Kirchhoff's Voltage Law
Ohm's Law
Faraday's Law
Explanation - KCL states that total current entering a junction equals total current leaving the junction.
Correct answer is: Kirchhoff's Current Law
Q.13 In a series circuit, how does total resistance change if more resistors are added?
Increases
Decreases
Remains same
Becomes zero
Explanation - In series, total resistance is the sum of individual resistances, so adding more increases R_total.
Correct answer is: Increases
Q.14 If a 10Ω resistor has 5V across it, the current flowing is:
0.5 A
2 A
5 A
50 A
Explanation - I = V/R = 5/10 = 0.5 A.
Correct answer is: 0.5 A
Q.15 Which of the following is a unit of electrical energy?
Joule
Watt
Ampere
Volt
Explanation - Energy = Power × Time, measured in Joules (J).
Correct answer is: Joule
Q.16 A 12V battery is connected across a series combination of 2Ω and 4Ω resistors. The current through the circuit is:
2 A
4 A
1 A
0.5 A
Explanation - Total resistance = 2 + 4 = 6Ω, I = V/R = 12/6 = 2 A.
Correct answer is: 2 A
Q.17 Electrical conductivity is the reciprocal of:
Resistivity
Resistance
Current
Voltage
Explanation - Conductivity σ = 1/ρ, where ρ is resistivity.
Correct answer is: Resistivity
Q.18 If the power dissipated in a resistor is constant, doubling the resistance will:
Double the current
Halve the current
Double the voltage
No effect
Explanation - P = I²R. For constant P, I = sqrt(P/R). Doubling R decreases I by factor sqrt(1/2), approximately halving.
Correct answer is: Halve the current
Q.19 Which of the following statements is correct about an ideal conductor?
Has zero resistance
Has infinite resistance
Has finite resistance
Blocks current
Explanation - An ideal conductor offers no opposition to current, so its resistance is zero.
Correct answer is: Has zero resistance
Q.20 A resistor is connected across 10V and dissipates 5W power. Its resistance is:
5Ω
20Ω
10Ω
2Ω
Explanation - P = V²/R ⇒ R = V²/P = 10²/5 = 100/5 = 20Ω.
Correct answer is: 20Ω
Q.21 Which component is used to vary resistance in a circuit?
Potentiometer
Voltmeter
Ammeter
Battery
Explanation - A potentiometer is a variable resistor used to adjust voltage or current.
Correct answer is: Potentiometer
Q.22 Which type of current is supplied by a battery?
Alternating Current
Direct Current
Pulsating Current
None
Explanation - A battery provides a unidirectional flow of electrons, called direct current (DC).
Correct answer is: Direct Current
Q.23 The internal resistance of a battery affects:
Current delivered
Voltage across terminals
Power delivered
All of these
Explanation - Internal resistance reduces terminal voltage, limits current, and affects power output.
Correct answer is: All of these
Q.24 The ratio of voltage to current in a circuit is called:
Conductance
Resistance
Capacitance
Inductance
Explanation - Resistance R = V/I, according to Ohm's Law.
Correct answer is: Resistance
Q.25 Which of the following is a good conductor but has higher resistance than copper?
Aluminum
Gold
Silver
Iron
Explanation - Aluminum conducts electricity well but has higher resistivity than copper, hence higher resistance for the same dimensions.
Correct answer is: Aluminum