Question 216: EM waves

Question

The electric field part of an electromagnetic wave in a medium is represented by E
x
= 0;
$${E_y} = 2.5{N \over C}\cos \left[ {\left( {2\pi  	imes {{10}^6}{{rad} \over m}} ight)t - \left( {\pi  	imes {{10}^{ - 2}}{{rad} \over s}} ight)x} ight];$$
E
z
= 0.

Accepted Answer

Since coefficient of x is negative, but is moving along +ve x-axis,
so This is the form E
y
= E
0
($$\omega $$t Ã¢ÂÂ kx)
$$\omega $$ = $${2\pi  	imes {{10}^6}}$$
f = $${\omega  \over {2\pi }}$$ = 10
6
Hz
k = $$\pi  	imes {10^{ - 2}}$$
Also, $$\lambda  = {{2\pi } \over k}$$ = $${{2\pi } \over {\pi  	imes {{10}^{ - 2}}}}$$ = 200 m

Answer

moving along x direction with frequency 10
6
Hz and wavelength 100 m.

Answer

moving along x direction with frequency 10
6
Hz and wavelength 200 m.

Answer

moving along $$-$$x direction with frequency 10
6
Hz and wavelength 200 m.

Answer

moving along y direction with frequency $$2\pi  	imes {10^6}\,Hz$$ and wavelength 200 m.

EM waves

The electric field part of an electromagnetic wave in a medium is represented by E x = 0; ${E_y} = 2.5{N \over C}\cos \left[ {\left( {2\pi \times {{10}^6}{{rad} \over m}} \right)t - \left( {\pi \times {{10}^{ - 2}}{{rad} \over s}} \right)x} \right];$ E z = 0.

Choose the correct answer: