Three observers $A, B$ and $C$ measure the speed of light coming from a source. Observer $A$ moves towards the source,observer $C$ moves away from the source with the same speed,and observer $B$ remains stationary. The surrounding space is a vacuum everywhere. Which of the following is true regarding the measured speeds ${v_A}, {v_B}$ and ${v_C}$?

Which of the following is/are the property/properties of a monochromatic electromagnetic wave propagating in the free space?
$1$. Electric and magnetic fields will have a phase difference $\frac{\pi}{2}$.
$2$. The energy of the wave is distributed equally between electric and magnetic fields.
$3$. The pressure exerted by the wave is the product of its speed and energy density.
$4$. The speed of the wave is equal to the ratio of the magnetic field to the electric field.

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:

Let $E_0$ and $B_0$ denote the amplitude of the electric and magnetic fields of a plane electromagnetic wave in air. The magnitude of the average momentum transferred per unit area and per unit time to a totally absorbing surface is

The electric field in an electromagnetic wave is given as $\vec{E} = 20 \sin \omega (t - \frac{x}{c}) \hat{j} \text{ N/C}$. Where $\omega$ and $c$ are the angular frequency and velocity of the electromagnetic wave,respectively. The energy contained in a volume of $5 \times 10^{-4} \text{ m}^3$ will be $..... \times 10^{-13} \text{ J}$. (Given $\varepsilon_0 = 8.85 \times 10^{-12} \text{ C}^2/\text{Nm}^2$)

Light is an electromagnetic wave. Its speed in vacuum is given by the expression