Question

In a plane E.M. wave, the electric field oscillates sinusoidally at a frequency of $2.5\times {10}^{10}\text{Hz}$ and amplitude $480\text{V/m}$. The amplitude of oscillating magnetic field will be

• A. $1.52\times {10}^{-8}{\text{Wb/m}}^2$
• B. $1.52\times {10}^{-7}{\text{Wb/m}}^2$
• C. $1.6\times {10}^{-6}{\text{Wb/m}}^2$
• D. $1.6\times {10}^{-7}{\text{Wb/m}}^2$

Answer 1

The correct option is C $1.6\times {10}^{-6}{\text{Wb/m}}^2$

Speed of EM wave is $c=\frac{E}{B}$
$B=\frac{E}{c}=\frac{480}{3\times {10}^8}=160\times {10}^{-8}$
$B=1.6\times {10}^{-6}{\text{Wb/m}}^2$