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

Ohm's law V = IR holds for:

A. Insulators

B. Semiconductors only

C. Ohmic conductors at constant temperature

D. All materials

Answer: Option C

Solution (By JKExamLibrary)

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.

This question belongs to: Science Physics

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Which of the following is not a unit of energy?

A. Joule

B. Watt

C. Electron volt

D. Kilowatt-hour

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Correct Answer: Option B

Explanation:
Watt is unit of power (J/s). Kilowatt-hour is energy (power × time). Joule is SI unit of energy. Electron volt is energy unit (1.6×10⁻¹⁹ J). Remember: power = energy/time. So watt is not energy.

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Question #2 Report Error

The loudness of sound depends on

A. Speed

B. Amplitude

C. Frequency

D. Wavelength

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Correct Answer: Option B

Explanation:
Loudness correlates with intensity, which is proportional to square of amplitude. Frequency determines pitch. Larger amplitude → louder sound. Measured in decibels.

This question belongs to: Science Physics

Question #3 Report Error

Sound cannot travel through:

A. Gases

B. Liquids

C. Vacuum

D. Solids

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Correct Answer: Option C

Explanation:
Sound requires material medium for mechanical wave propagation. Vacuum lacks particles to transmit vibrations. Light (EM wave) travels through vacuum. Memory tip: 'Sound = mechanical wave ⇒ needs medium; light = EM wave ⇒ no medium needed'. Fundamental wave property frequently tested in competitive exams to assess medium-dependence understanding.

This question belongs to: Science Physics

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