The magnetic field in a plane electromagnetic wave is given by $B_y=2\times {10}^{-7}$$\sin \left(0.5\times {10}^{3}x+1.5\times {10}^{11}t\right)$.  This electromagnetic wave is

We have,   $B_y=2\times {10}^{-7}\sin \left(0.5\times {10}^{3}x+1.5\times {10}^{11}t\right)$

Comparing with the standard equation, we get

$B_y=B_0\sin (kx+\omega t)$

$k=0.5\times {10}^3$

Wavelength,   $\lambda =\frac{2\pi }{0.5\times {10}^3}=0.01256 \mathrm{m} \left(\because \lambda =\frac{2\pi }{k}\right)$

The wavelength range of microwaves is 10^-3 m to 0.1 m. The wavelength of this wave lies between 10^-3 m to 0.1 m, so the equation represents a microwave.