Title: The Telephone
1The Telephone
transmitter
loudspeaker
(Sound energy to electrical energy)
(Electrical energy to sound energy)
2Printed circuit board of the telephone
3An Older Telephone
4Using an oscilloscope
1) Quiet sound, low frequency
2) Quiet sound, high frequency
3) Loud sound, low frequency
4) Loud sound, high frequency
5Telecommunication Optical Fibres
- The law of reflection.
- When a ray of light bounces off a mirror , the
angle going in equals the angle coming out. - The line at right angles to the mirror is called
the normal.
6Optical Fibres
- When light is incident on a glass surface,
refraction or bending of the light takes place. - The light comes out of the glass.
- This however is dependent on the angle i.
7Finding the Critical Angle
1) Ray gets refracted
2) Ray still gets refracted
4) Ray gets internally reflected
3) Ray still gets refracted (just!)
8Optical Fibres
- Optical fibres are made of thin flexible glass
threads. - They are about the size of a human hair.
- The fibres have a protective coating which keeps
the light inside the fibre.
9Satellites
- Interactive summary.
- Satellites which orbit the earth every 24____
are called ________ satellites. - They are above the _____ point on the _____ .
- Satellites use ______ dishes to _______ the
microwave signals. - The microwave signals travel in _______ lines.
10(No Transcript)
11(No Transcript)
12(No Transcript)
13(No Transcript)