Tag: speed of light and optical density

An electromagnetic wave passing through the space is given by equations $E=E _o\sin(wt-kx), B=B _0\sin(wt-kx)$ which of the following is true?

If a source of power $4kW$ produces $10^{20}$ photons/second, the radiation belongs to a part of the spectrum called:

For a medium with permitivity $\epsilon$ and permeability $\mu$, the velocity of light is given by:

If $C=$ the velocity of light, which of the following is correct?

The wave function (in S.I. units) for an electromagnetic wave is given as-
$\psi (x, t) = 10^{3} \sin \pi (3\times 10^{6} x - 9\times 10^{14}t)$ The speed of the wave is:

The electric field part of an electromagnetic wave in a medium is represented by $ { E } _{ x }=0 $ ;
$ { E } _{ y }=2.5\frac { N }{ C } cos[(2\pi \times { 10 }^{ 6 }\frac { rad }{ s } )t-(\pi \times { 10 }^{ -2 }\frac { rad }{ m } )x] $ ;
$ { E } _{ z }=0 $.The wave is:

The velocity of electromagnetic waves in free space is $3 \times 10^6 m/sec$. The frequency of a radio wave of wavelength $150 m$, is:-

If $v _s$ , $v _x$ and $v _m$ are the velocities of soft gamma rays, X-rays and Microwaves respectively in vacuum, then

If velocity of an electromagnetic wave in a medium is $3\times 10^8m/s$ then find refractive index of medium.

Three observers $A,B$ and $C$ measure the speed of light coming from a source as $v _A,v _B$ and $v _C$. Observer $A$ moves towards the source, $C$ moves away from source and $B$ stays stationary. The surrounding medium is water. If A and C are moving at the same speed, then