SS3 First Term Physics Lesson Note – Electromagnetic Waves

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WEEK 1

ELECTROMAGNETIC WAVES

CONTENT

• Definition and Concept
• Types of radiation
• Detectors
• Uses

DEFINITION AND CONCEPT

Electromagnetic waves are produced by electromagnetic vibrations. Electromagnetic waves have electrical origin and the ability to travel in vacuum.  So, electromagnetic waves are regarded as a combination of traveling electric and magnetic forces which vary in value and are directed at right angles to each other and to the direction of travel.  In other words, they are transverse waves.

TYPES OF RADIATION

The electromagnetic waves consist of the following:

1. Radio waves with wavelength 10^-3m to 1000m.
2. Infra-red waves with average wavelengths of 10^-6m.
3. Visible spectrum, known as light waves, with wavelengths of 7 x 10^-7 m for red rays.
4. Ultraviolet rays with wavelength of 10^-8m
5. X-rays with wavelength of 10^-10 m.
6. Gamma –rays with wavelength of 10^-11m.

 

1. Radio waves: Radio waves have the longest wavelengths.  Radio waves are emitted from transmitters and carry radio signals to radio sets.  The shortest radio waves are called microwaves.  Microwaves are used in radar and in heating hence they are used in cooking
2. Infra-red waves: Infra-red waves are found just beyond the red end of the visible spectrum. They are present in the radiation from the sun or from the filament of an electric lamp.

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