1. Senior Science Information systems
Part 3 – Properties of electromagnetic waves

2. 2 identify the properties of energy from the electromagnetic spectrum that make it useful in communication technologies including its – speed of travel – ability to travel in a straight line – ability to be reflected

3. Speed of light
All waves in the electromagnetic spectrum travel at the same speed–the speed of light. Light travels at km per second. All electromagnetic waves travel at this speed.
It might be difficult to comprehend just how quickly these waves travel. An electromagnetic wave can travel around the Earth more than six times in one second.

4. activity Speed of light
Use a pencil to draw a cartoon demonstrating electromagnetic waves travelling at high speed. Be as inventive as you like!

5. Speed of light benefits in communication
Telecommunications benefit from the speed of information transfer as phone calls and satellite communications from across the globe, such as the transmission of live television programs from other countries, are achieved at a fast rate without time delay.

6. Travels in a straight line
Electromagnetic waves travel in straight lines unless acted on by a influencing field. This is an important aspect of electromagnetic waves as they can be directed to a specific receiving dish, allowing line of sight transmissions in communications eg. microwave transmissions from telecommunications towers.
This property of electromagnetic waves also allows waves detected from space to be used to pinpoint the location of the transmitting signal. This allows scientists to locate and map stars and galaxies, control astronomical instruments on satellites and track the passage of spacecraft through space.

7. Travels in a straight line Benefits on communication
Electromagnetic waves can be focused to a point for collection at a distance due to the fact that the waves travel in straight lines. The location of stars, galaxies and space shuttles can also be pin pointed due to this property of electromagnetic waves.

8. Ability to be reflected
Electromagnetic waves can be reflected off surfaces. This is a very important property of electromagnetic waves. Reflection allows:
waves to be transmitted across the globe using the reflective properties of the ionosphere and the Earth’s surface a weak signal to be collected by a receiving dish.

9. Ability to be reflected
activity
Ability to be reflected
Label the following on the diagram below based on the information from the previous paragraph:
transmitter
reflected wave
ionosphere

10. Ability to be reflected
activity
Ability to be reflected

11. Ability to be reflected
Waves can be collected and reflected to a single point by a satellite dish.
Pay TV delivered without cables relies on information transfer in this way. Telecommunications towers also rely on the principles of wave reflection at the satellite dish. Communication with space shuttles and receiving information from space probes in outer space relies on the same principles–on a much larger scale.

12. Ability to be reflected Benefits on communication
The reflective capabilities of electromagnetic waves allows waves to be reflected to a receiver. This is important in communication from space, pay TV using satellite dish technology and telecommunications. Electromagnetic waves being reflected off atmospheric layers allows transmission further around the globe without the use of repeater stations eg. radio wave transmissions.

13. 1 identify that where information systems cannot be physically linked the information may be transmitted in wave form through the atmosphere or space 3 describe the individual properties of visible light, radio waves (AM, FM, TV) and microwaves and relate these to their use in communication systems

14. Radio
Spotlight Pg
Summarise and answer Set 1 and Set 2 questions

15. TV
Spotlight Pg
Summarise and answer Set 1