Question

In a plane electromagnetic wave, the magnetic field is given by \(B = 400 \times 10^{-6}\sin[(4.0 \times 10^{-4})(t - x/c)]\). The peak value of electric field (in V m\(^{-1}\)) is

• A. \(8 \times 10^4\)
• B. \(6 \times 10^4\)
• C. \(4 \times 10^4\)
• D. \(3 \times 10^4\)
• E. \(12 \times 10^4\)

Hint:

In EM waves: \(E = cB\).

Answer 1

Answer: (E)

Concept: \[ E = cB \]

Step 1: Substitute values.
\[ E = 3 \times 10^8 \times 400 \times 10^{-6} \]

Step 2: Solve.
\[ E = 12 \times 10^4 \, V/m \]