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www.GOALias.blogspot.com8.4.6 X-raysBeyond the UV region of the electromagnetic spectrum lies the X-rayregion. We are familiar with X-rays because of its medical applications. Itcovers wavelengths from about 10 –8 m (10 nm) down to 10 –13 m(10 –4 nm). One common way to generate X-rays is to bombard a metaltarget by high energy electrons. X-rays are used as a diagnostic tool inmedicine and as a treatment for certain forms of cancer. Because X-raysdamage or destroy living tissues and organisms, care must be taken toavoid unnecessary or over exposure.8.4.7 Gamma raysThey lie in the upper frequency range of the electromagnetic spectrumand have wavelengths of from about 10 –10 m to less than 10 –14 m. Thishigh frequency radiation is produced in nuclear reactions andalso emitted by radioactive nuclei. They are used in medicine to destroycancer cells.Table 8.1 summarises different types of electromagnetic waves, theirproduction and detections. As mentioned earlier, the demarcationbetween different region is not sharp and there are over laps.ElectromagneticWavesTABLE 8.1 DIFFERENT TYPES OF ELECTROMAGNETIC WAVESType Wavelength range Production DetectionRadio > 0.1 m Rapid acceleration and Receiver’s aerialsdecelerations of electronsin aerialsMicrowave 0.1m to 1 mm Klystron valve or Point contact diodesmagnetron valveInfra-red 1mm to 700 nm Vibration of atoms Thermopilesand moleculesBolometer, Infraredphotographic filmLight 700 nm to 400 nm Electrons in atoms emit The eyelight when they move from Photocellsone energy level to aPhotographic filmlower energy levelUltraviolet 400 nm to 1nm Inner shell electrons in Photocellsatoms moving from one Photographic filmenergy level to a lower levelX-rays 1nm to 10 –3 nm X-ray tubes or inner shell Photographic filmelectronsGeiger tubesIonisation chamberGamma rays