Maxwell's Equations — CompletenessHardQuestion 20251
Question
Which of Maxwell's four equations correctly predicts electromagnetic waves?
- AGauss's law for E alone
- BGauss's law for B alone
- CFaraday's law and the modified Ampere's law togetherCorrect
- DLorentz force law
Correct answer
Faraday's law and the modified Ampere's law together
Explanation
Faraday: changing B creates E (curl E = −∂B/∂t). Modified Ampere: changing E creates B (curl B = μ₀J + μ₀ε₀ ∂E/∂t). Together they predict that a changing E field creates a changing B field which creates a changing E field — self-sustaining electromagnetic waves propagating at c = 1/√(μ₀ε₀).