An antenna is placed in a dielectric medium of dielectric constant $6.25$. If the maximum size of that antenna is $5.0\, mm$. it can radiate a signal of minimum frequency of $GHz .$
(Given $\mu_{ r }=1$ for dielectric medium)
$60$
$6$
$9$
$3$
The energy associated with electric field is $(U_E)$ and with magnetic field is $(U_B)$ for an electromagnetic wave in free space. Then
Write standard equation for waves.
If ${\varepsilon _0}$ and ${\mu _0}$ are respectively, the electric permittivity and the magnetic permeability of free space. $\varepsilon $ and $\mu $ the corresponding quantities in a medium, the refractive index of the medium is
The electric field component of an electromagnetic wave in vaccum is given as $\vec E = 3\cos \,\left( {1.8y + 5.4 \times {{10}^8}\,t} \right)\hat i$ Its direction of propagation and wavelength is
If a source of electromagnetic radiation having power $15 kW$ produces $10^{16}$ photons per second, the radiation belongs to a part of spectrum is.(Take Planck constant $h =6 \times 10^{-34}\,Js$ )