Question

The oscillating magnetic field in a plane electromagnetic wave is given by By = \(5 × 10^{–6}\) \(sin\;1000\;π(5x – 4 × 108\;t)T\). The amplitude of electric field will be:

• A. \(15 × 10^2\) \(Vm^{–1}\)
• B. \(5 × 10^{–6}\) \(Vm^{–1}\)
• C. \(16 × 10^{12} \;Vm^{–1}\)
• D. \(4 × 10^2\) \(Vm^{–1}\)

Answer 1

The Correct Option is D

We know that the Speed of light :  \(c = \frac{ω }{ k}\) 

= \(\frac{4 × 10^8}{5} = 0.8 × 10^8\) \(m/sec\)

Therefore,  \(E_0 = cB_0\)

=\( 0.8 × 10^8 × 5 × 10^{–6}\)

= \(400\) \(V/m\)

= \(4 × 10^{–2}\)

Hence, the correct option is (D): \(4 × 10^{–2}\; Vm^{-1}\)