Jagdish Chandra Bose produced electromagnetic waves of which range?

Light is an electromagnetic wave. Its speed in vacuum is given by the expression

In an $EM$ wave propagating along the $X-$ direction,the magnetic field oscillates at a frequency of $3 \times 10^{10} \, Hz$ along the $Y-$ direction and has an amplitude of $10^{-7} \, T$. The expression for the electric field will be:

The rms value of the electric field of the light coming from the sun is $720 \ N/C$. The average total energy density of the electromagnetic wave is $:-$

An electromagnetic wave travelling in $x$-direction is described by field equation $E_y = 300 \sin \omega \left( t - \frac{x}{c} \right)$. If the electron is restricted to move in $y$-direction only with speed of $1.5 \times 10^6 \text{ m/s}$, then the ratio of maximum electric and magnetic forces acting on the electron is . . . . . . .

What are electromagnetic waves?