Electromagnetic spectrum e learning
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Transcript of Electromagnetic spectrum e learning
ELECTROMAGNETIC SPECTRUM
Objectives
Describe the 7 main components of the electromagnetic spectrum
State the properties of electromagnetic waves (EM wave)
State the applications of electromagnetic waves
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
Rich Men In Vegas Use X-ray Goggles
How is electromagnetic waves form?
Created by accelerating electric charges, moving the charges back and forth
Produce oscillating magnetic and electric field
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.
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
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
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
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
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
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
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.
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.