Ohm's law V = IR holds for: MCQ with Answer and Explanation

Ohm's law V = IR holds for:
A. Ohmic conductors at constant temperature
B. Semiconductors only
C. All materials
D. Insulators
Answer: Option A
Solution (By JKSSB Mock Tests)
Ohm's law applies to ohmic materials (metals) at constant temperature. Non-ohmic devices (diodes, filaments) have nonlinear V-I characteristics. Memory tip: 'Ohmic = linear V-I graph through origin; temperature must be constant'. Conceptual question testing Ohm's law limitations, frequently examined in competitive exams.

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Practice More Physics Questions

Question #1
A particle performs Simple Harmonic Motion (SHM). If its displacement from the mean position is half of its amplitude, the ratio of its kinetic energy to potential energy is:
A. 2:1
B. 1:3
C. 3:1
D. 1:1

Correct Answer: Option C


Explanation:
In SHM, Total Energy (E) = 1/2 k A^2. Potential Energy (U) at displacement x is 1/2 k x^2. Kinetic Energy (K) is E - U = 1/2 k (A^2 - x^2). Given x = A/2. U = 1/2 k (A/2)^2 = 1/2 k (A^2 / 4) = E/4. Since total energy is conserved, K = E - E/4 = 3E/4. The ratio of Kinetic to Potential Energy (K:U) is (3E/4) / (E/4) = 3:1.

This question belongs to: Science Physics
Question #2
The number of neutrons in ²³⁸₉₂U is
A. 238
B. 146
C. 92
D. 330

Correct Answer: Option B


Explanation:
Neutrons = A - Z = 238 - 92 = 146.

This question belongs to: Science Physics
Question #3
A flywheel rotates at 120 rpm. Angular velocity in rad/s is
A. 4π
B. 6π
C. 2π
D. π

Correct Answer: Option A


Explanation:
ω = 2π × (rpm/60) = 2π × 120/60 = 4π rad/s.

This question belongs to: Science Physics