$A$ plane electromagnetic wave in a non-magnetic dielectric medium is given by $\vec{E} = \vec{E}_0 \sin(4 \times 10^7 x - 50t)$,where distance is in meters and time is in seconds. The dielectric constant of the medium is:

$A$ lamp emits monochromatic green light uniformly in all directions. The lamp is $3\%$ efficient in converting electrical power to electromagnetic waves and consumes $100\,W$ of power. The amplitude of the electric field associated with the electromagnetic radiation at a distance of $5\,m$ from the lamp will be nearly.......$V/m$

The electric field in a plane electromagnetic wave is given by $E_z = 60 \cos(5x + 1.5 \times 10^9 t) \text{ V/m}$. Then the expression for the corresponding magnetic field is (here subscripts denote the direction of the field):

The electric field of a plane electromagnetic wave, travelling in an unknown non-magnetic medium is given by, $E_y = 20 \sin(3 \times 10^6 x - 4.5 \times 10^{14} t) \text{ V/m}$ (where $x, t$ and other values are in $S$.$I$. units). The dielectric constant of the medium is . . . . . . . (Speed of light in free space is $c = 3 \times 10^8 \text{ m/s}$)

In a plane electromagnetic wave,the maximum value of the electric field component is $4.4 \ Vm^{-1}$. The intensity of the wave is nearly (in $mW \ m^{-2}$)

$A$ point source of $100\,W$ emits light with $5\%$ efficiency. At a distance of $5\,m$ from the source,the intensity produced by the electric field component is: