Chapter 13 Electromagnetic Waves

Question 1

Are EM waves transverse or longitudinal

Answer 1

transverse

Question 2

At what speed does the electromagn waves travel at?

Answer 2

the speed of light, 3.0×108 in vacuum

Question 3

How are electromagnetic waves applied in our lives?

Answer 3

Components
Application
Radio Waves
Radio and television communication
Microwaves
Satellite television and mobile phone networks
Microwave oven - microwaves of a particle wavelength are very strongly absorbed by water molecules, heats up the water and cooks food
Infrared Radiation
Infrared sensors used in thermal imaging equipment Remote control for television
Intruder alarm & surveillance systems to detect intruders
Visible Light
(violent – 380nm, red – 700nm)
Laser light - Light Amplification by Stimulated Emission of Radiation Telecommunication through optical fibres using short pulses of light Medical equipment using laser or optic fibre
Ultraviolent Ray Main source: sunlight
Sun lamps & sun beds
Sterilise surgical instruments in UV sterilisation boxes Fluorescent chemicals to coat inside of fluorescent light tubes
X-rays
Diagnostic tool in medicine and dentistry, to observe the inner parts of one’s body (fractures etc…) Examine flaws and cracks in metal parts joined together
Inspect insides of articles such as the insides of luggage Cancer treatment
Gamma rays
Emitted due to the decay of radioactive nuclei, released during nuclear reactions. Cause serious damage when absorbed by living tissues.
Used under controlled conditions to kill cancerous cells and sterilise hospital equipment Check for flaws in metals