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

Intensity in terms of electric field `U_(av) =1/2epsilon_(0) E_(0)^(2)`
Intensity in terms of magnetic field `U_(av) =1/2 (B_(0)^(2))/(mu_(0))`
Now taking the intensity in terms of electric field.
`(U_(av)) " electric field " =1/2 epsilon_(0) E_(0)^(2)`
`rArr " " =1/2 epsilon_(0) (cB_(0))^(2) " " (E_(0) =cB_(0))`
`=1/2 epsilon_(0) xx c^(2)B^(2)` ,
`" But "" " c = (1)/(sqrt(mu_(0)epsilon_(0))`
`:. " "(U_(av)) _("Electric field") = 1/2 epsilon_(0) xx (1)/(mu_(0)epsilon_(0)) B_(0)^(2) = 1/2 (B_(0)^(2))/(mu_(0))`
`=(U_(av))_("magnetic field")`
Thus the energy in electromagnetic wave is divided equally between electric field vector and magnetic field vector.
Therefore the of contributions by the electric field and magnetic field components to the intensity of an electromagnetic wave is `1:1`