Chapter Exam

Chapter 5: Electromagnetic Waves — Online MCQ Test

Q: Which one of the following is the correct relationship between the speed of electromagnetic waves in vacuum and the speed of light?

Answer: B. They are the same — Electromagnetic waves travel in vacuum with speed equal to the speed of light, c = 3 × 10^8 m s^-1.

Q: The displacement current introduced by Maxwell is associated with:

Answer: C. A changing electric field — Displacement current arises due to a time-varying electric field, even in regions where no conduction current exists.

Q: Maxwell’s displacement current term was introduced mainly to make which law consistent?

Answer: C. Ampere’s circuital law — The displacement current term modifies Ampere’s law so that it remains valid for time-varying electric fields.

PHYSICS · CLASS 12th · Tamil Nadu State Board

Practice Chapter 5: Electromagnetic Waves with a free chapter-wise online MCQ test for Tamil Nadu State Board CLASS 12th PHYSICS. This chapter covers: This chapter introduces displacement current Maxwell equations and electromagnetic spectrum characteristics. Students explore properties applications and wave propagation modes for.... AI-generated questions from basic to board-exam level, with instant results and explanations.

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Chapter 5: Electromagnetic Waves — Important Questions & Answers (FAQ)

Frequently asked questions from Tamil Nadu State Board CLASS 12th PHYSICS — Chapter 5: Electromagnetic Waves, with answers and explanations. These are sample questions; the exam has its own separate question set.

Which one of the following is the correct relationship between the speed of electromagnetic waves in vacuum and the speed of light?

A. They are different
B. They are the same ✓
C. Electromagnetic waves travel slower than light
D. Electromagnetic waves do not travel in vacuum

Answer: B. They are the same
Electromagnetic waves travel in vacuum with speed equal to the speed of light, c = 3 × 10^8 m s^-1.

The displacement current introduced by Maxwell is associated with:

A. A changing magnetic field only
B. A constant electric field only
C. A changing electric field ✓
D. The motion of electrons in a wire only

Answer: C. A changing electric field
Displacement current arises due to a time-varying electric field, even in regions where no conduction current exists.

Maxwell’s displacement current term was introduced mainly to make which law consistent?

A. Faraday’s law
B. Coulomb’s law
C. Ampere’s circuital law ✓
D. Ohm’s law

Answer: C. Ampere’s circuital law
The displacement current term modifies Ampere’s law so that it remains valid for time-varying electric fields.

Which statement correctly compares radio waves and gamma rays?

A. Radio waves have higher frequency than gamma rays
B. Gamma rays have longer wavelength than radio waves
C. Radio waves have lower frequency and longer wavelength than gamma rays ✓
D. Both have the same frequency but different amplitudes

Answer: C. Radio waves have lower frequency and longer wavelength than gamma rays
Radio waves occupy the low-frequency, long-wavelength end of the spectrum, while gamma rays are at the high-frequency, short-wavelength end.

Which one of the following is the correct order of the electromagnetic spectrum from lower to higher frequency?

A. Gamma rays, X-rays, ultraviolet, visible, infrared
B. Infrared, visible, ultraviolet, X-rays, gamma rays ✓
C. Visible, infrared, ultraviolet, gamma rays, X-rays
D. Radio waves, gamma rays, microwaves, infrared, visible

Answer: B. Infrared, visible, ultraviolet, X-rays, gamma rays
Frequency increases in the order infrared → visible → ultraviolet → X-rays → gamma rays.