An electromagnetic wave of frequency $5\, GHz$ is travelling in a medium whose relative electric permittivity and relative magnetic permeability both are $2$. Its velocity in this medium is $\times 10^{7}\, m/s$.

Which of the following statements is false regarding the properties of electromagnetic waves?

An electromagnetic wave of frequency $1 \times 10^{14} \, Hz$ is propagating along the $z$-axis. The amplitude of the electric field is $4 \, V/m$. If $\varepsilon_0 = 8.8 \times 10^{-12} \, C^2/N \cdot m^2$,then the average energy density of the electric field will be:

If $\vec E$ and $\vec B$ represent the electric and magnetic field vectors of an electromagnetic wave,then the direction of propagation of the electromagnetic wave is in the direction of

About $20 \%$ of the power of a $100 \ W$ bulb is converted to visible radiation. Assuming that the radiation is emitted isotropically and neglecting reflection,the average intensity of visible radiation at a distance of $5 \ m$ is $\frac{\alpha}{25 \pi} \ W/m^2$. The value of $\alpha$ is

The condition under which a microwave oven heats up a food item containing water molecules most efficiently is