### Electromagnetic Waves

goals
$X-$ray falling on a material
The wave emitted by any atom or molecule must have some finite total length which is known as coherence length. For sodium light, this length is $2\ cm$.
A wave has wavelength $50A^o$.
Instantaneous displacement current $1A$ in the space between the parallel plates of $1\mu F$ capacitor can be established by changing the potential difference at the rate of:
The waves which can not travel in vacuum are :