The telephone
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The Telephone. transmitter. loudspeaker. (Sound energy to electrical energy). (Electrical energy to sound energy). Printed circuit board of the telephone. An Older Telephone. Using an oscilloscope. 1) Quiet sound, low frequency:. 2) Quiet sound, high frequency:.

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The telephone l.jpg
The Telephone



(Sound energy to

electrical energy)

(Electrical energy

to sound energy)

Using an oscilloscope l.jpg
Using an oscilloscope

1) Quiet sound, low frequency:

2) Quiet sound, high frequency:

3) Loud sound, low frequency:

4) Loud sound, high frequency:

Telecommunication optical fibres l.jpg

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.

Telecommunication Optical Fibres

Optical fibres l.jpg

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.

Optical Fibres

Finding the critical angle l.jpg

THE CRITICAL ANGLE bending of the light takes place.

Finding the Critical Angle…

1) Ray gets refracted

2) Ray still gets refracted

4) Ray gets internally reflected

3) Ray still gets refracted (just!)

Optical fibres8 l.jpg
Optical Fibres bending of the light takes place.

  • 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.

Satellites l.jpg
Satellites bending of the light takes place.

  • 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.