2. Objectives
Describe the 7 main components of the
electromagnetic spectrum
State the properties of electromagnetic waves
(EM wave)
State the applications of electromagnetic
waves
3. What are Electromagnetic
waves?
Consist of 7 components
Radio waves
Microwaves
Infra-red radiation
Visible light
Ultra-violet waves
X-rays
Gamma rays
105 m
10-14 m
Wavelength
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4.
5. How is electromagnetic waves
form?
Created by accelerating electric charges,
moving the charges back and forth
Produce oscillating magnetic and electric field
6. Electromagnetic Waves
Electromagnetic spectrum is continuous.
No distinct boundaries between each
component.
Gamma rays have the shortest wavelength
and highest frequency.
Radio waves have the longest wavelength and
lowest frequency.
7. Properties of Electromagnetic
waves
Transfer energy from one place to another
They are transverse waves
Travel through vacuum with the speed of light
(3 x 108 m s-1)
Show wave properties like reflection and
refraction
Obey wave equation v = fλ
8. Application of Electromagnetic
waves
Radio waves (10-1 to 105)
Longest wavelengths
Able to go around obstructions due to their
long wavelength
Used in radio broadcasting,
telephone transmission, television,
radar, navigation system
9. Microwaves (10-3 to 10-1)
Microwave oven – cause the water molecules
in the food to vibrate. The vibration causes
friction at a molecular level which will heat up
the food.
Satellite communication and television –
signals are transmitted through aerial dishes
to satellites in the space.
Application of Electromagnetic
waves
10. Infra-red Radiation (10-7 to 10-3)
All object emit infra-red radiation
We experience infrared-radiation in the form of
heat
Ear thermometer: measure the amount of infra-
red radiation that emanates from the eardrum.
Used in remote controls for electronic devices and
infra-red motion detectors.
Application of Electromagnetic
waves
11. Visible Light (10-7)
Only part of the EM spectrum that can be
detected by human eye.
Wavelength: 700nm (red) to 400nm (violet)
Laser can be used in industries
to weld metals together and in
medicine.
Optical fibres in telecommunications
Application of Electromagnetic
waves
12. Application of Electromagnetic
waves
Ultra-Violet (UV) Radiation (10-8 to 10-7)
Sunlight is the main source of UV radiation
Ultraviolet lamps are used in sunbeds for
artificial tanning.
Used in hospital for sterilisation - kill bacteria
and viruses
13. Application of Electromagnetic
waves
X-Rays (10-13 to 10-8)
used to produce the X-ray images to examine
a person’s body or tooth decay
used in X-ray scanners in airports
can penetrate through all materials except
lead.