The electromagnetic waves travel with a velocity

The ratio of the magnitudes of the electric field and $10^8$ times the magnetic field of a plane electromagnetic wave is

The magnetic field in a plane electromagnetic wave is given by
$B_y = (2 \times 10^{-7}) \sin (0.5 \times 10^3 x + 1.5 \times 10^{11} t) \, T$
$(a)$ What is the wavelength and frequency of the wave?
$(b)$ Write an expression for the electric field.

If a source is transmitting electromagnetic waves of frequency $8.2 \times 10^6 \,Hz$, then the wavelength of the electromagnetic waves transmitted from the source will be (in $\,m$)

The biological importance of the ozone layer is that:

Which of the following combinations has the dimension of electrical resistance? (Here,$\varepsilon_0$ is the permittivity of vacuum and $\mu_0$ is the permeability of vacuum.)