If $c$ is the speed of electromagnetic waves in vacuum,its speed in a medium of dielectric constant $K$ and relative permeability $\mu_r$ is:

$A$ light bulb emits power of $800 \, W$. What is the maximum value of the magnetic field at a distance of $3.5 \, m$ from the bulb?

$A$ mathematical representation of an electromagnetic wave is given by the two equations $E = E_{max} \cos(kx - \omega t)$ and $B = B_{max} \cos(kx - \omega t)$,where $E_{max}$ is the amplitude of the electric field and $B_{max}$ is the amplitude of the magnetic field. What is the intensity $I$ in terms of $E_{max}$ and universal constants $\mu_0, \epsilon_0$?

$A$ plane electromagnetic wave with a frequency of $30 \text{ MHz}$ travels in free space. At a particular point in space and time,the electric field is $6 \text{ V/m}$. The magnetic field at this point will be $x \times 10^{-8} \text{ T}$. The value of $x$ is ..... .

The efficiency of a bulb of power $60 \ W$ is $16 \%$. The peak value of the electric field produced by the electromagnetic radiation from the bulb at a distance of $2 \ m$ from the bulb is $\left(\frac{1}{4 \pi \epsilon_0}=9 \times 10^9 \ Nm^2 C^{-2}\right)$ (in $Vm^{-1}$)

An electromagnetic wave is represented by the electric field $\vec{E} = E_0 \hat{n} \sin [\omega t + (6y - 8z)]$. Taking unit vectors in $x, y$ and $z$ directions to be $\hat{i}, \hat{j}$ and $\hat{k}$,the direction of propagation $\hat{s}$ is: