Skip to main content
Chapter 20 of 29
Flashcards

Electromagnetic Waves

Kerala Board · Class 12 · Physics

Flashcards for Electromagnetic Waves — Kerala Board Class 12 Physics. Quick Q&A cards covering key concepts, definitions, and formulas.

44 questions24 flashcards5 concepts
24 Flashcards
Card 1Displacement Current

What is displacement current and why was it introduced by Maxwell?

Answer

Displacement current is an equivalent current that flows due to a changing electric field, just like conduction current produces magnetic field. Maxwell introduced it to resolve the inconsistency in A

Card 2Displacement Current

Write the mathematical expression for displacement current.

Answer

Displacement current: id = ε₀(dΦE/dt), where ε₀ is the permittivity of free space and ΦE is electric flux. For a capacitor with area A and electric field E: id = ε₀A(dE/dt). This equals the conduction

Card 3Maxwell's Equations

State the modified Ampere's law (Ampere-Maxwell law).

Answer

∮B⃗·dl⃗ = μ₀(i + id) = μ₀i + μ₀ε₀(dΦE/dt), where i is conduction current and id is displacement current. This law states that both conduction current and changing electric field produce magnetic field

Card 4Maxwell's Equations

List all four Maxwell's equations.

Answer

1. ∮E⃗·ds⃗ = q/ε₀ (Gauss law for electricity) 2. ∮B⃗·ds⃗ = 0 (Gauss law for magnetism) 3. ∮E⃗·dl⃗ = -dΦB/dt (Faraday's law) 4. ∮B⃗·dl⃗ = μ₀i + μ₀ε₀(dΦE/dt) (Ampere-Maxwell law)

Card 5Electromagnetic Waves

What is an electromagnetic wave and how is it generated?

Answer

An electromagnetic wave consists of oscillating electric and magnetic fields perpendicular to each other and to the direction of propagation. It is generated by accelerated charges. The oscillating el

Card 6Electromagnetic Waves

Write the mathematical expressions for electric and magnetic fields in an electromagnetic wave.

Answer

For a wave propagating in z-direction: Electric field: Ex = E₀ sin(kz - ωt) Magnetic field: By = B₀ sin(kz - ωt) where k = 2π/λ is wave vector magnitude and ω is angular frequency.

Card 7Electromagnetic Waves

What is the relationship between electric and magnetic field amplitudes in an electromagnetic wave?

Answer

B₀ = E₀/c, where c is speed of light in vacuum. Also, the instantaneous relationship is B = E/c. The magnetic field amplitude is much smaller than electric field amplitude numerically due to the large

Card 8Electromagnetic Waves

What is the speed of electromagnetic waves in vacuum and in a medium?

Answer

In vacuum: c = 1/√(μ₀ε₀) = 3×10⁸ m/s In a medium: v = 1/√(με), where μ is permeability and ε is permittivity of the medium. Speed in medium is always less than in vacuum.

+16 more flashcards available

Practice All

Get detailed flashcards for Electromagnetic Waves

Super Tutor gives you interactive content for every chapter of Kerala Board Class 12 Physics — summaries, quizzes, flashcards, and more.

Try Super Tutor — It's Free

Frequently Asked Questions

What are the important topics in Electromagnetic Waves for Kerala Board Class 12 Physics?

Electromagnetic Waves covers several key topics that are frequently asked in Kerala Board Class 12 board exams. Focus on the core concepts listed on this page and practise related questions to build confidence.

Start by understanding all key concepts. Practise previous year questions from this chapter. Revise formulas and definitions regularly. Use flashcards for quick revision before the exam.

There are 24 flashcards for Electromagnetic Waves covering key definitions, formulas, and concepts. Use them daily for 10–15 minutes for best results.

Sources & Official References

Content is aligned to the official syllabus. Refer to the board website for the latest curriculum.