STANDARDPhysics-Electromagnetic Waves
STANDARD Physics Wave Vector MCQ Question
Type: MCQ-numerical-Medium-Class 12
The electric field associated with an electromagnetic wave in vacuum is given by E = 40cos(kz - 6 × 10⁸t) V/m, where E, z and t are in volt per metre, metre and second respectively. The value of wave vector k is
A
2 m⁻¹
B
0.5 m⁻¹
C
6 m⁻¹
D
3 m⁻¹
Correct Answer
Option A
Detailed Explanation
Compare the given equation with E = E₀ cos(kz - ωt). We get, ω = 6 × 10⁸ s⁻¹. Wave vector, k = ω/c = 6 × 10⁸ s⁻¹ / 3 × 10⁸ m/s = 2 m⁻¹.
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