Out of the following options,which one can be used to produce a propagating electromagnetic wave?

The speed of an electromagnetic wave in a vacuum depends upon the source of radiation.

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 the magnetic field in a plane electromagnetic wave is given by $\overrightarrow{B} = 3 \times 10^{-8} \sin (1.6 \times 10^{3} x + 48 \times 10^{10} t) \hat{j} \; T$,then what will be the expression for the electric field?

Electromagnetic waves are incident normally on a perfectly reflecting surface having surface area $A$. If $I$ is the intensity of the incident electromagnetic radiation and $c$ is the speed of light in vacuum,the force exerted by the electromagnetic wave on the reflecting surface is

An electromagnetic wave has a frequency of $3 \text{ MHz}$ in free space. When this wave passes through a medium with a relative permittivity $\varepsilon_r = 4.0$,its frequency will be: