Q.

For a transparent medium relative permeability and permittivity, μr and εr are 1.0 and 1.44 respectively. The velocity of light in this medium would be           [2019]
 

1 2.5×108 m/s  
2 3×108 m/s  
3 2.08×108 m/s  
4 4.32×108 m/s  

Ans.

(1)

Given: relative permittivity, εr=1.44 and relative permeability, μr=1

Now, as we know that, εr=εε0ε=εrε0

and μr=μμ0μ=μrμ0

where, ε and μ are the permittivity and permeability of the medium.

    Velocity of light in the medium will be

v=1με=1μrμ0εrε0=cμrεr=3×1081×1.44

  =2.5×108m/s