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CHAPTER 16- ELECTRONICS AND INFORMATION AND

COMMUNICATION TECHNOLOGY

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WAVES

. generated by forces

that cause vibrations or

oscillations to a system.

..tranfer energy from onepoint to another.

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TWO TYPE OF WAVES

MECHANICAL WAVES

ELECTROMAGNETIC

WAVES

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MECHANICAL WAVES

. generated vibrations oroscillations of particles or object.

example: sound waves

.require a medium to travel in,travel through solid ( wall ), through

liquid( water ), through gases

(atmosphere ). cannot through a vacumm( outer

space)

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Electromagnetic Waves

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Properties of Electromagnetic

Waves

Electromagnetic Wave- A transverse

wave consisting of oscillating electric

and magnetic fields at right angles to

each other

The spectrum includes more than visible

light- not all light is visible to the human

eye

Light is a wave and also a particle

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The Electromagnetic Spectrum

Electromagnetic waves vary depending on

frequency and wavelength

http://upload.wikimedia.org/wikipedia/commons/f/f0/EM_Spectrum_Properties.svg

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Properties of the Electromagnetic Spectrum

Waves in the electromagnetic

spectrum vary in size from very

long radio waves the size ofbuildings, to very short

gamma-rays smaller than the

size of the nucleus of an atom.

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Properties of the Electromagnetic Spectrum

FREQUENCYis the

number of waves generated

per unit time.

OR

number of crest or

troughs passing through a

particular point in one

second.

Unit for frequency,

hertz (Hz), f

WAVE VELOCITY

distance travel by a waveper unit time , metres per

second (ms-1), v

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Radio Waves

Radio waves have the longestwavelengths in the electromagnetic

spectrum. These waves can be longer

than a football field or as short as afootball. Radio waves do more than

just bring music to your radio. They

also carry signals for your television

and cellular phones.

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Radio Waves

Objects in space, such as planets and

comets, giant clouds of gas and dust,

and stars and galaxies, emit light at

many different wavelengths. Some ofthe light they emit has very large

wavelengths - sometimes as long as a

mile! These long waves are in theradio region of the electromagnetic

spectrum.

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Speed of Electromagnetic Waves

All electromagnetic waves move at the speed

of light

Remember

Speed= wavelength x frequency

Only the wavelength and frequency change

This change decides which type of

electromagnetic wave it is (radio, gamma, etc.)

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Speed of Light

The speed of light in a vacuum=

2.99792458 x 108 m/s

The speed of light in air= 2.99709 x 108

m/s

We use 3 x 108m/s which equates to

300 million meters per second!

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RESISTORS