If $E$ and $B$ denote electric and magnetic fields respectively,which of the following is dimensionless?

$A$ plane electromagnetic wave of intensity $6 \, W/m^2$ strikes a small mirror of area $30 \, cm^2$,held perpendicular to the approaching wave. The momentum transmitted in $kg \cdot m/s$ by the wave to the mirror each second will be:

The electric and the magnetic field,associated with an electromagnetic wave propagating along the $+z$-axis,can be represented by

The magnetic field of a plane electromagnetic wave is given by $\vec B = B_0 \hat i \cos(kz - \omega t) + B_1 \hat j \cos(kz - \omega t)$,where $B_0 = 3 \times 10^{-5} \, T$ and $B_1 = 2 \times 10^{-6} \, T$. The rms value of the force experienced by a stationary charge $Q = 10^{-4} \, C$ at $z = 0$ is closest to:

The direction of the Poynting vector represents:

$A$ plane electromagnetic wave of frequency $25 \text{ MHz}$ propagates in vacuum along the positive $x$-direction. At a particular point in space and time,if the electric field is $6.3 \hat{j} \text{ Vm}^{-1}$,then the magnitude of the magnetic field of the wave at this point at the same time is: