The ratio of contributions made by the electric 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

Energy of electric field `U=(1)/(2)in_(0)E_(0)^(2)`
Energy of magnetic field `U=(B_(0)^(2))/(2mu_(0))`
Relation between electric and magnetic field,
`E_(0)=cB_(0)`
`therefore (1)/(2)in_(0)E_(0)^(2)=(1)/(2)in_(0)(cB_(0))^(2)`
`=(1)/(2)in_(0)c^(2)B_(0)^(2)`
`=(1)/(2)in_(0)xx(B_(0)^(2))/(mu_(0)in_(0))[because c=(1)/(sqrt(mu_(0)in_(0)))]`
`=(B^(2))/(2mu_(0))`
Thus, energy of electromagnetic waves is equally distributed in electric field and magnetic field. Intensity of electric field and magnetic field and magnetic field are equal. Hence, ratio is 1 : 1.