Mada za sehemu hiiWavesMada 5
- Introduction to Waves
- Sound Waves
- Musical Sound
- Electromagnetic Spectrum
- Applications of Electromagnetic Wave in Daily Life
The electromagnetic spectrum is the range of all possible frequencies of electromagnetic radiation. The "electromagnetic spectrum" of an object has a different meaning, and is instead the characteristic distribution of electromagnetic radiation emitted or absorbed by that particular object
The electromagnetic spectrum extends from below the low frequencies used for modern radio communication to gamma radiation at the short-wavelength (high frequency) end, thereby covering wavelengths from thousands of kilometers down to a fraction of the size of an atom.
- It is continuous i.e each band merges into the next and there are no gaps in the frequencies.
- In some case, there is an overlap in the range of wavelength. This is because sometimes the name given to the wave (radiation) is determined by the source and not the wavelength.
- Radio waves
- Microwaves
- Infrared waves.
Radio waves are a type of electromagnetic radiation with the longest wavelengths in the electromagnetic spectrum. Radio waves have frequencies from 300GHz to as low as 3kHz, and corresponding wavelengths ranging from 1 millimeter (0.039in) to 100 kilometers (62mi).
Sources of radio waves
- Alternating electric currents flowing in antennae
- Oscillators
- Planets, comets, stars and galaxies
Microwaves have a short wavelength of between m to about 0.1.
Sources
Are produced by oscillation of charges in special antennae mounted on dishes.
They have the frequency 0f between 10 and 10 Hz. They lie between the visible light and microwaves. They have the heating effect.
Sources
Vibration of atoms and molecules due to their thermal energy. All hot bodies emit infrared radiations
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