The electric field part of an electromagnetic wave in a medium is represented by :
`E_(x) = 0`
`E_(y)=2.5(N)/(C) cos[(2pixx10^(6)("rad")/(m))t-(pi xx 10^(-2) ("rad")/(s))x]`
`E_(z)=0`. The wave is :

Options

A. moving along x direction with frequency `10^(6)` Hz and wavelength 100m
B. moving along x direction with frequency `10^(6)` Hz and wavelength 200 m
C. moving along `-x` direction with frequency `10^(6)` Hz and wavelength 200 m
D. moving along `y` direction with frequency `2pixx10^(6)` Hz and wavelength 200 m

Answer

B

Explanation

`E_(y)=2.5(N)/(C)xxcos[(2pixx10^(6)("rad")/("m"))t-(pixx10^(-2)("rad")/(s))x]`
`E_(z)=0, E_(x)=0`
The wave is moving in the positive direction of x.
This is in the form `E_(y)=E_(0)cos(omegat-kx)`
`omega=2pixx10^(6)`
`2pi upsilon=2pixx10^(6)" "rArr" "upsilon=10^(6)Hz`
`(2pi)/(lambda)=krArr (2pi)/(lambda)=pixx10^(-2)or lambda=200m`