CHAPTER 16- ELECTRONICS AND INFORMATION AND COMMUNICATION TECHNOLOGY

WAVES…. generated by forces that cause vibrations or oscillations to a system.

..tranfer energy from one point to another.

TWO TYPE OF WAVESMECHANICAL WAVES

ELECTROMAGNETIC WAVES

MECHANICAL WAVES

…. generated vibrations or oscillations 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)

Electromagnetic Waves

About Electromagnetic Waves

When you listen to the radio, watch TV, or cook dinner in a microwave oven, you are using electromagnetic waves.

Radio waves, television waves, and microwaves are all types of electromagnetic waves. They differ from each other in wavelength. Wavelength is the distance between one wave crest to the next.

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

The Electromagnetic Spectrum

Electromagnetic waves vary depending on frequency and wavelength

Properties of the Electromagnetic Spectrum

Waves in the electromagnetic spectrum vary in size from very long radio waves the size of buildings, to very short gamma-rays smaller than the size of the nucleus of an atom.

Properties of the Electromagnetic Spectrum

FREQUENCY – is 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 wave per unit time , metres per second (ms-1), v

Different types of waves

Radio Waves- longest wavelength. AM/FM, TV Microwaves- 2nd longest wavelength. Radar,

Microwaves Infrared Waves- 3rd longest wavelength. Infrared

photography, night vision Visible Light- 4th longest wavelength. Microscope,

astronomy Ultraviolet Light- 5th longest wavelength. Sterilization X Rays- 6th longest wavelength. Medical exam of teeth

and bones Gamma Rays- Shortest wavelength. Used in cancer

treatment and food irradiation

Radio Waves

Radio waves have the longest wavelengths in the electromagnetic spectrum. These waves can be longer than a football field or as short as a football. Radio waves do more than just bring music to your radio. They also carry signals for your television and cellular phones.

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 of the light they emit has very large wavelengths - sometimes as long as a mile! These long waves are in the radio region of the electromagnetic spectrum.

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.)

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/sWe use 3 x 108 m/s which equates to

300 million meters per second!

Electronic component for radio

RESISTORS