The ratio of the electric field $(E)$ to the magnetic field $(B)$ in an electromagnetic wave gives which physical quantity?

Energy stored in electromagnetic oscillations is in the form of

Calculate the electric and magnetic fields produced by the radiation coming from a $100\; W$ bulb at a distance of $3\; m$. Assume that the efficiency of the bulb is $2.5\%$ and it is a point source.

The average power output of a point source of an electromagnetic radiation is $1080 \,W$. The maximum value of the rms value of the electric field at a distance of $3 \,m$ from the source is (in $\,Vm^{-1}$)

If a source is transmitting electromagnetic waves of frequency $8.196 \times 10^{6} \ Hz$,then the wavelength of the $EM$ waves transmitted from the source will be . . . . . . . (in $cm$)

In an electromagnetic wave,what has an average value of zero?