The ratio of contributions made by the eletric field and magnetic field components to the intensity of an `EM` wave is.

Options

A. `c:1`
B. `c^(2):1`
C. `1:1`
D. `sqrt(c ):1`

Answer

C

Explanation

The intensity of electromagnetic wave is given by `I=U_(av)c`, where `U_(av)=` Average enery and `c=` speed of light
Intensity in relation with electric field `U_(av)=(1)/(2)epsilon_(0)E_(0)^(2)`
Intensity relation with magnetic filed `U_(av)=(1)/(2)(B_(0)^(2))/(mu_(0))`
Now taking the intensity in terms of electric field
`(U_(av))_("electric filed")=(1)/(2)epsilon_(0)(cB_(0))^(2)` (`:' E_(0)=cB_(0)`)
But `c=(1)/(sqrt(mu_(0)epsilon_(0)))`
`:. (U_(av))_("Electric filed")=(1)/(2)epsilon_(0)xx(1)/(mu_(0)epsilon_(0))B_(0)^(2)=(1)/(2)(B_(0)^(2))/(mu_(0))`
`=(U_(av))_("magnetic field")`
Hence the energy in electromagnetic wave divided equally between electric filed vector and magnetic field vector
It means the ratio of contribution by the electric filed and magnetic field components to the intensity of an electromagnetic wave is `1:1`