When we have an accident, we often go to the hospital to have an X-Ray taken to see if there is a broken bone. The X-Ray is a shadow picture. X-Rays pass through the part of the body being X-Rayed and cast shadows on the film.
The film is coated with a sensitive emulsion on both sides and on being exposed, it develops like an ordinary photographic film.
The X-Ray does not pass through bones and other objects, so, it casts denser shadows, which show up as light areas on the film. This will show the doctor if any bone has been broken or dislocated.
Below X-Ray info from Wikipedia (Read More):-
X-radiation (composed of X-rays) is a form of electromagnetic radiation. X-rays have a wavelength in the range of 10 to 0.01 nanometers, corresponding to frequencies in the range 30 petahertz to 30 exahertz (3 × 1016 Hz to 3 × 1019 Hz) and energies in the range 120 eV to 120 keV. They are shorter in wavelength than UV rays. In many languages, X-radiation is called Röntgen radiation after Wilhelm Conrad Röntgen, who is generally credited as their discoverer, and who had called them X-rays to signify an unknown type of radiation.
http://en.wikipedia.org/wiki/X-ray
