The electric field part of an electromagnetic wave in a medium is represented by ` E_x=0, `
` Ey =2.5 (N)/(C) cos [( 2pi xx 10^(6) (rad)/( m ) ) t- (pi xx 10^(-2) ("rad")/( s)) x ], E_z=0 `The wave is

Options

A. Moving along y direction with frequency `2pi xx 10^(9)` Hz and wavelength 200 m.
B. Moving along x direction with frequency `10^(6)` Hr and wave length 100 m.
C. Moving along x direction with frequency `10^(6)` Hr and wave length 200 m.
D. Moving along -x direction with frequency `10^(6)` Hr and wave length 200 m.

Answer

C

Explanation

Comparing the given equation
` E = 2.5 (N)/( C) cos [ (2pi xx 10^6 ("rad")/("sec" ) ) t - (pi xx 20^(-2) ("rad")/( "sec" ) )x ]`
With the standard equation
`E_(y) = E_(0) cos (omega t - kx)`
We get
`omega = 2pi f = 2pi xx 10^(6)`
`therefore f = 10^(6)` Hz
Moreover, we know that
`(2pi)/( lambda) = k = pi xx 10^(-2) m^(-1)`
`rArr lambda = 200` m