Question

If the magnetic field of a plane electromagnetic wave is given by $B=100\times {10}^{-6}\sin [2\pi \times 2\times {10}^5(t-\frac{x}{c})]$ then the maximum electric field associated with it is
(The speed of light $=3\times {10}^8\text{m/s}$)

• A. $6\times {10}^4\text{N/C}$
• B. $4\times {10}^4\text{N/C}$
• C. $3\times {10}^4\text{N/C}$
• D. $4.5\times {10}^4\text{N/C}$

Answer 1

The correct option is C $3\times {10}^4\text{N/C}$

Given:
Magnetic field of a plane EMW
$B=100\times {10}^{-6}\sin [2\pi \times 2\times {10}^5(t-\frac{x}{c})]$
The speed of light $=3\times {10}^8\text{m/s}$
$\Rightarrow B_0=100\times {10}^{-6}\text{in tesla (T) Units}$

Using, formula

$E_0=B_0\times C$

$=100\times {10}^{-6}\times 3\times {10}^8=3\times {10}^4\text{N/C}$

Hence, option $\left(B\right)$ is correct.