Question

The magnetic field of an electromagnetic wave is given by
$ B_{y}=3 \times 10^{-7}\,sin\left(10^{3}\,x +6.28 \times 10^{12}t\right) $ .
The wavelength of the electromagnetic wave is

• A. $ 6.28\,cm $
• B. $ 3.14\,cm $
• C. $ 0.63\,cm $
• D. $ 0.32\,cm $

Answer 1

Answer: (C)

Given, $B_{y}=3\times10^{-7} sin(10^{3}\,x+6.28\times 10^{12}t)$
Comparing with the general equation
$B_{y}=B_{0}\,sin (kx+\omega t)$
we get $k=10^{3}$
or $\frac{2\pi}{\lambda}=10^{3} \left[k=\frac{2\pi}{\lambda}\right]$
$\Rightarrow \lambda=\frac{2\pi}{10^{3}}$
$=6.28\times10^{-3}m $
$=0.63\,cm$