EM radiation.pptx medical physics 2nd sem

med c

1. Electromagnetic radiation

2. definition The movement of energy, through space or a medium composed of both electric and magnetic waves, travelling at the speed of light.

3. These waves oscillates at frequencies varying from a few cycles per second to more than 10 20 cycles per second. The electric and magnetic waves have oscillations that are oriented at 90 degrees to each other and 90 degrees to the direction of travel.

4. Electromagnetic spectrum The range of wavelengths or frequencies over which the electromagnetic radiations extend is called an electromagnetic spectrum.

5. RELATION BETWEEN FREQUENCY AND WAVELENGTH As the frequency increases the wavelength decreases and with increasing frequencies the amount of energy that the waves carry also increase. v = f × λ

6. INFRARED RADIATION Infrared radiation , or simply infrared is electromagnetic radiation (EMR) with longer wavelengths than those of visible light , and is therefore invinsible. They have a wavelength of 10 -5 meters and a frequency of 10 12 hertz. They are produced by oscillation of molecules, from all objects at temperatures above absolute zero .

7. uses They can be used to study human and animal body heat patterns. Most remote controls operate by sending pulses of infrared. Infrared lampsare used to treat skin diseases and relieve the pain of sore muscles. They are used for drying painted and enameled surfaces, leather, metals, papers and textiles.

8. Ultraviolet rays Ultraviolet means beyond violet in Latin and are electromagnetic radiation just beyond what our eyes can see on the violet side of the rainbow. They have a wavelength of 10 -8 meters and a frequency of 10 16 hertz . The main source of UV rays is the SUN

9. Uses Ultraviolet rays can be used to kill microbes . So it is usedin hospitals for sterlization of instruments. Suitable doses of Ultraviolet rays cause the body to produce vitamin D. Phototherapy To fight counterfeiting

10. dangers One of the most common effects of UV exposure is "erythema", also known as sunburn. Large doses of UV can damage the retina Skin cancer Aging

11. X-rays X rays are electromagnetic radiation that differentially penetrates structures within the body and creates images of these structures on photographic film. They have a wavelength of 10 -10 meters and a frequency of 10 18 hertz. They are generated by rapid deleceration of fast moving electrons.

12. uses It acts as a diagnostic tool in dentistry and medicine . Custom officers at airports inspect the content of your luggage using X-rays. Check for cracks in metal plates.

13. danger Risk of cancers

14. Visible light Visible light is defined as the wavelengths that are visible to most human eyes . Visible light is made of seven colors each with a different wavelength and different frequency. They have a wavelength of 0.5 -6 meters and a frequency of 10 15 hertz.

15. uses Helps us see Photosynthesis in plants Lasers

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