The document describes the electromagnetic spectrum and its applications. It states that the electromagnetic spectrum consists of 7 main components from radio waves to gamma rays, which are classified based on their wavelength. Electromagnetic waves transfer energy, travel at the speed of light, and exhibit wave properties. The different types of electromagnetic waves have various applications, such as radio waves for communication technologies, microwaves for wireless devices and cooking, infrared for thermal imaging, visible light for sight and lasers, ultraviolet for sterilization, X-rays for medical imaging, and gamma rays for cancer treatment.

1. ELECTROMAGNET
IC SPECTRUM

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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Goggles

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.

14. Application of Electromagnetic
waves
Gamma Rays (10-14 to 10-10)
 It can be used to treat cancer by killing cancer
cells.
 Cause serious damages to living tissues.