When someone is injured, a 999 call to the emergency services will make sure an ambulance is there as soon as possible. Sometimes, the paramedics from the land ambulance will decide the patient will need to be transported by Air Ambulance. The crew of the land ambulance and Air Ambulance communicate on a special radio frequency. In Devon, this frequency is about 170 MHz FM. Ambulance services in, London, Northern Ireland and Scotland use the same frequencies.

1. (a)

Explain what is meant by the term frequency.

___________________________________________________________ ___________________________________________________________ (b) (c)

What is the name of the unit of frequency? __________________ Radio waves travel at a speed of 300x106m/s in air. Calculate the approximate wavelength of the radio wave.

___________________________________________________________ ___________________________________________________________ ___________________________________________________________ wavelength = ____________ m

2. Radio waves are part of the electromagnetic spectrum. Finish the diagram of the electromagnetic spectrum. visible light increasing frequency

3. Sometimes, radio frequencies interfere with each other. Describe how interference occurs. (Drawing a diagram may be helpful.) ___________________________________________________________ ___________________________________________________________ ___________________________________________________________ ___________________________________________________________ ___________________________________________________________

4. Suggest why ambulance services in London, Northern Ireland and Scotland use the same frequency as Devon but South Wales, Avon and Dorset do not. ___________________________________________________________ ___________________________________________________________