ELECTROMAGNETIC WAVES SECONDARY 3 PHYSICS

WHAT ARE EM WAVES? Electromagnetic waves (EM waves for short) are waves that can travel in a vacuum. These waves are created by the vibration of an electric charge.

Electromagnetic Spectrum It is a group of different electromagnetic waves. There are 7 components in the spectrum.

Electromagnetic Spectrum Gamma rays X – rays Ultraviolet Visible light Infra-red Microwaves Radio waves Highest frequency Shortest wavelength Lowest frequency Longest wavelength

Uses of Gamma Rays Kill cancer cells Study the nucleus in atoms

Uses of X-rays Take ‘pictures’ of bones in the body Study the crystal structure of crystalline substances Check for cracks in metal plates

Uses of Ultraviolet Detect counterfeit notes Gives the clothes a ‘glow’ effect in discotheques Sun-tanning Sterilise medical equipment

Uses of Visible Light Enable us to see things Photosynthesis in plants

Uses of Infra-red Heating Haze photography

Uses of Microwaves Radar communication Analysis of the molecular and atomic structure Telephone communications

Uses of Radio Waves Radar communications TV and radio broadcasting

Common Properties of EM Waves All transverse waves All travel at the speed of light. (3 x 108 m/s) Can travel through solid, liquid, gas and vacuum Obey the laws of reflection and refraction All can be absorbed and emitted by matter The wave equation is applicable to all