Answer: 3 × 10⁸ m/s.
- A 3 × 10⁸ m/s
- B 1 × 10⁸ m/s
- C 6 × 10⁸ m/s
- D 1.5 × 10⁸ m/s
Correct answer: A. 3 × 10⁸ m/s
Explanation: c = 1/√(μ_0ε_0) = 1/√(4π×10⁻⁷ × 8.85×10⁻¹²) = 1/√(1.11×10⁻¹⁷) = 1/(3.33×10⁻⁹) ≈ 3×10⁸ m/s. This is how Maxwell first derived the speed of light.
In an electromagnetic wave, the oscillating electric field (E) and magnetic field (B) are perpendicular to each other and to the direction the wave travels - a purely transverse wave that needs no medium, unlike sound.
Concept context
Maxwell's equations, EM spectrum, properties, and applications of each band.