In an electromagnetic wave, the amplitude of electric field is $1 V/m.$ the frequency of wave is $5 \times {10^{14}}\,Hz$. The wave is propagating along $z-$ axis. The average energy density of electric field, in $Joule/m^3$, will be
$1.1 \times {10^{ - 11}}$
$2.2 \times {10^{ - 12}}$
$3.3 \times {10^{ - 13}}$
$4.4 \times {10^{ - 14}}$
What happens to the intensity of light from a bulb if the distance from the bulb is doubled? As a laser beam travels across the length of a room, its intensity essentially remains constant. What geometrical characteristic of $LASER$ beam is responsible for the constant intensity which is missing in the case of light from the bulb ?
An $EM$ wave propagating in $x$-direction has a wavelength of $8\,mm$. The electric field vibrating $y$ direction has maximum magnitude of $60\,Vm ^{-1}$. Choose the correct equations for electric and magnetic fields if the $EM$ wave is propagating in vacuum
The mean intensity of radiation on the surface of the Sun is about $10^{8}\,W/m^2.$ The $rms$ value of the corresponding magnetic field is closet to
A radiation is emitted by $1000\, W$ bulb and it generates an electric field and magnetic field at $P$, placed at a distance of $2\, m$. The efficiency of the bulb is $1.25 \%$. The value of peak electric field at $P$ is $x \times 10^{-1} \,V / m$. Value of $x$ is. (Rounded-off to the nearest integer)
[Take $\varepsilon_{0}=8.85 \times 10^{-12} C ^{2} N ^{-1} m ^{-2}, c =3 \times 10^{8}$ $ms ^{-1}$ ]
Given below are two statements:
Statement $I$ : A time varying electric field is a source of changing magnetic field and vice-versa. Thus a disturbance in electric or magnetic field creates $EM$ waves.
Statement $II$ : In a material medium. The $EM$ wave travels with speed $v =\frac{1}{\sqrt{\mu_{0} \varepsilon_{0}}}$.
In the light of the above statements, choose the correct answer from the options given below