PHYSICS - The Electromagnetic Spectrum

Longest to Shortest of the EM waves:

• Radio
• Micro
• Infra-red
• Visible light
• Ultra Violet
• X-rays
• Gamma

Radio Waves have:

• Longest wavelength
• Lowest frequency
• Least energy
• Least dangerous

(^This is the opposite for Gamma rays)

The Electro Magnetic Spectrum

• All EM waves are transverse waves
• They form part of a continuous spectrum
• EM waves vary in wavelength from arounf 10^-15 m to more than 10^4 m
• All the different types of EM waves travel at the same speed (3x10^8 mp) in a vaccum       (e.g. space)
• EM waves with higher frequencies have shorter wavelengths
• EM waves are non mechanical
• THEY ALL TRAVEL AT THE SAME SPEED

GAMMA RAYS AND X-RAYS

X-rays:

• A white sheet of paper is placed under the patients injury (e.g. their hand)
• Then, the x-ray tube is //stitched// on, x-rays from the tube pass through the patient's body. They leave a shadow image on the film shwing the bones.
• When the film is developed, the parts exposed to the x-rays are darker than the other parts. So, the bones appear lighter than the surrounding tissue which appears dark. The developed film shows a 'negative image' of the bones.
• Uses: securety tests (airports), medical, aircrafts

Gamma Rays:

• Gamma radiation is the electromagnetic radiation from radioactive substances. Gamma rays and X-rays have similar wavelengths so they have similar properties.
• Uses: to kill harmful substances, to sterilise surgical instruments, to kill cancer cells
• Lead is a very dense metal. It can be used to absorb gamma rays and x-rays.
• X-rays and Gamma rays will penetrate thin metal sheets

Radio Therapy:

• Is used to destroy cancerous tumors. A narrow beam of gamma radiation is directed at the tumor. The beam is aimed at it from different directions in order to kill the tumor but not the surrounding tissue. The cobalt-60 source, which produces gamma rays, is a thick lead container.

Ionising Radiation:

• Includes Gamma, x-ray and UV
• High doses can kill cells
• Lower doses can cause mutations/ damage the cells that can result in tumors (cancers)

Protection:

• X-rays:
• radiographer hides behind a screen or leaves the room
• use a lead aipron to protect sensitve areas
• use a film badge, it tells you…