Frequencies in the UHF range normally propagate by means of

A light of intensity $$12 \mathrm{Wm}^{-2}$$ incidents on a black surface of area $$4 \mathrm{~cm}^2$$. The radiation pressure on the surface is

The electric field $$(E)$$ and magnetic field $$(B)$$ of an electromagnetic wave passing through vacuum are given by

$$\begin{aligned} & E=E_0 \sin (k x-\omega t) \\ & B=B_0 \sin (k x-\omega t) \end{aligned}$$

Then the correct statement among the following is

A carrier wave is used to transmit a message signal. If the peak voltage of modulating signal and carrier signal are increased by $$1 \%$$ and $$3 \%$$ respectively, the modulation index is changed by