Chapter Exam

Chapter-3 Current Electricity — Online MCQ Test

Q: Ohm's law states that:

Answer: A. V = IR — Ohm's law mathematically expresses the relationship: Voltage = Current × Resistance, or V = IR, for an ohmic conductor at constant temperature.

Q: The relationship between drift velocity (vd) and current (I) is:

Answer: A. I ∝ vd — Current is directly proportional to drift velocity: I = nAevd, where n is electron density, A is cross-sectional area, and e is electron charge.

Q: A conductor has a resistance of 10Ω at 0°C. If its temperature coefficient of resistance is 0.005/°C, its resistance at 100°C will be approximately:

Answer: A. 15Ω — Using R = R₀(1 + αΔT), where R₀ = 10Ω, α = 0.005/°C, ΔT = 100°C: R = 10(1 + 0.005 × 100) = 10(1.5) = 15Ω.

Q: A battery with EMF E and negligible internal resistance is connected to a network of resistors. Using Kirchhoff's junction rule at a specific junction, if currents I₁ (3A entering), I₂ (5A leaving), and I₃ (unknown) meet, then I₃ is:

Answer: A. 2A entering — By Kirchhoff's junction rule: ΣIin = ΣIout. So 3A + I₃ = 5A, giving I₃ = 2A entering the junction.

PHYSICS · CLASS 12 SECOND PUC · Karnataka State Board

Practice Chapter-3 Current Electricity with a free chapter-wise online MCQ test for Karnataka State Board CLASS 12 SECOND PUC PHYSICS. This chapter covers: drift velocity - Ohm's law - resistance - V-I characteristics - Kirchhoff's laws - Wheatstone bridge - internal resistance. AI-generated questions from basic to board-exam level, with instant results and explanations.

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Chapter-3 Current Electricity — Important Questions & Answers (FAQ)

Frequently asked questions from Karnataka State Board CLASS 12 SECOND PUC PHYSICS — Chapter-3 Current Electricity, with answers and explanations. These are sample questions; the exam has its own separate question set.

Drift velocity is defined as:

A. The average velocity acquired by free electrons in the direction of electric field ✓
B. The instantaneous velocity of electrons at any moment
C. The velocity of electrons due to thermal motion
D. The maximum velocity electrons can achieve

Answer: A. The average velocity acquired by free electrons in the direction of electric field
Drift velocity is the average velocity with which free electrons move in the direction opposite to the applied electric field in a conductor.

Ohm's law states that:

A. V = IR ✓
B. V = I/R
C. I = VR
D. R = I/V

Answer: A. V = IR
Ohm's law mathematically expresses the relationship: Voltage = Current × Resistance, or V = IR, for an ohmic conductor at constant temperature.

The relationship between drift velocity (vd) and current (I) is:

A. I ∝ vd ✓
B. I ∝ 1/vd
C. I is independent of vd
D. I ∝ vd²

Answer: A. I ∝ vd
Current is directly proportional to drift velocity: I = nAevd, where n is electron density, A is cross-sectional area, and e is electron charge.

A conductor has a resistance of 10Ω at 0°C. If its temperature coefficient of resistance is 0.005/°C, its resistance at 100°C will be approximately:

A. 15Ω ✓
B. 10.5Ω
C. 15Ω
D. 20Ω

Answer: A. 15Ω
Using R = R₀(1 + αΔT), where R₀ = 10Ω, α = 0.005/°C, ΔT = 100°C: R = 10(1 + 0.005 × 100) = 10(1.5) = 15Ω.

A battery with EMF E and negligible internal resistance is connected to a network of resistors. Using Kirchhoff's junction rule at a specific junction, if currents I₁ (3A entering), I₂ (5A leaving), and I₃ (unknown) meet, then I₃ is: