Q. The electric field part of an electromagnetic wave in a medium is represented by$\ E_{x} = 0;$ $E_{y} = 2.5\frac{N}{C}\cos{\left\lbrack \left( 2\pi \times 10^{6}\frac{rad}{m} \right)t - \left( \pi \times 10^{- 2}\frac{rad}{s} \right)x \right\rbrack;}$ $E_{2} = 0.$ The wave is
A) Moving along $y$ direction with frequency $2\pi \times 10^{6}Hz$ and wavelength $200\ m$
B) Moving along $x$ direction with frequency $10^{6}Hz$ and wavelength $100\ m$
C) Moving along $x$ direction with frequency $10^{6}Hz$ and wavelength $200\ m$
D) Moving along $- x$ direction with frequency $10^{6}Hz$ and wavelength $200\ m$
Explanation
(c) Comparing the given equation with standard equation
$k = \frac{2\pi}{\lambda} = \pi \times 10^{- 2} \Rightarrow \lambda = 200\ m$
And $\omega = 2\pi v = 2\pi \times 10^{6} \Rightarrow v = 10^{6}Hz$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.