1. SENIOR SCIENCE INFORMATION SYSTEMS
Topic 4: Electrical Impulses

2. 1
identify communication technologies that transform one type of
energy into electrical energy 2
describe the transmission of images using digital technologies in
terms of scanning of the input image along very thin lines 3
explain how the coding of the image into a series of zeros and ones
allows its transmission and ultimate decoding

3. Coding and Decoding Information
Coding converts information into binary coded form which uses the digits 0 and 1. The digital transmission is by electrical, light or electromagnetic impulses representing the 0s and 1s. Decoding changes the 0s and 1s impulses received back to information which can be understood by the receiver.

4. Coding and Decoding Information

5. Faxes
Faxes information is optically scanned along very thin lines across the page.
A page is broken up into a grid consisting of very small boxes.
The scanner records the number one in the box when scanning a dark section and a zero when scanning a white section.
This light energy information is transformed by a photodiode into electrical energy and sent along phone lines.
The receiving fax machine puts ink in the small grid boxes with ones and leaves the boxes with zeros blank.

6. Energy Transformation Review

7. Energy Transformation Review

8. Generating Electrical Impulses
When you use batteries in your camera, walkman or remote control car, you are changing chemical energy from the batteries into electrical energy.
When you use a microphone, sound energy is converted into an electrical signal.
When an aerial receives radio waves, it converts these waves into an electrical signal.
The kinetic energy of the steam turns turbines which turn generators to produce electricity, thus turning kinetic energy into electrical energy.

9. Generating Electrical Impulses
Mobile phones and telephones change what form of energy into an electrical signal?
Televisions and radios change what form of energy into electrical signal?
Fax machines and long distance telephone lines (optical fibres) convert what form of energy into electrical energy?

10. Generating Electrical Impulses
Mobile phones and telephones change sound energy into electrical energy.
Televisions and radios change electromagnetic energy into electrical energy.
Fax machines and long distance telephone lines (optical fibres) convert light energy into electrical energy.

11. Review Spotlight Summarise pg 204-207
Answer “To Think About” Questions