Q 31 :

The ratio of speeds of electromagnetic waves in vacuum and a medium, having dielectric constant $k$ = 3 and permeability $\mu =2{\mu }_0,$ is

$\left({\mu }_0\text{=permeability of vacuum}\right)$   [2026]

• $\sqrt{6}:1$

   

• 3 : 2

   

• 36 : 1

   

• 6 : 1

   

Q 32 :

An electromagnetic wave of frequency 100 MHz propagates through a medium of conductivity,$\sigma =10\hspace{0.17em}mho/m$. The ratio of maximum conduction current density to maximum displacement current density is ______.

$\text{[Take }\frac{1}{4\pi {\epsilon }_0}=9\times {10}^9 {\text{N m}}^2/{\text{C}}^2\text{]}$           [2026]

Q 33 :

The electric field of an electromagnetic wave travelling through a medium is given by $\overrightarrow{E}(x,t)=25\sin (2.0\times {10}^{15}t-{10}^{7}x)\hat{n}.$ Then the refractive index of the medium is _____ 

(All given measurement are in SI units.)         [2026]

• 1.5

   

• 1.7

   

• 2

   

• 1.2