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X-rays are a part of the natural electromagnetic
spectrum. All electromagnetic waves travel at the same speed (velocity would
be more accurate, but we shall pass that!) through vacuum – 300,000 km/sec. A
wave has two attributes – wavelength and frequency. The product of the two
equals the speed at which it travels.
Waves with longer wavelength (lower frequency) have
lower energy. The shorter the wavelength, greater the energy of the wave. At
one end of the spectrum we have radio waves with wavelengths measured in
metres, centimetres or millimetres (frequencies range from few kiloHertz to
tens of megaHertz).
In the middle of the spectrum are heat waves (infrared),
visible light and ultraviolet rays. The shorter UV rays can be damaging to
life.
Beyond UV (still shorter wavelength or higher frequency)
are X-rays and the even more powerful gamma rays. Their high energy allows
them to penetrate through solid matter. They can cause serious damage to the
macromolecules of life.
X-rays (also called Röntgen rays after their discoverer)
were discovered and artificially produced in the laboratory towards the end of the 19th century.
All electromagnetic radiation can also be considered to
be particles (photons) travelling at the same speed but with different
energies. While sometimes it is convenient to regard them as such, we do not
have to enter that debate J.
X Rays
Key Points :
•X-rays are very high energy
electromagnetic waves.
•Though they resemble ‘light’ as we know
it, they cannot be ‘sensed’ by the eye.
•Though they are a tool for imaging,
their use is not without dangers!