WHAT HAPPENS WHEN A VIOLET OR RED LASER ARE SHONE AT A LUMINOUS SIGN?

1.“Home Team ” summarise properties and uses of : ‘Radio waves through to Infra-red’, into back of exercise books, and then memorise them - 15 minutes 2.“Away Teams” do the same for ‘UV through to Gamma’ 3. Close all exercise books! 4.Home Team pairs take it in turns to describe key points to opposing team – 5 minutes 5.Away Team pairs repeat above to the home team pair ELECTROMAGNETIC SPECTRUM

PROGRESS CHECK QUESTIONS 1.Which part of the EM spectrum has the longest wavelength? 2.Which part of the EM spectrum has the shortest wavelength 3.Which part of the EM spectrum has the highest frequency? 4.Which part of the EM spectrum has the lowest frequency? 5.List 3 properties of electromagnetic waves that make them special compared to other waves. 6.Which type of EM waves are the most dangerous? 7.Which type of EM wave can be used for both cooking and communication ?

CONTINUED 8. Which part of the EM is absorbed by the ozone layer and can cause skin cancer? 9. Which part of the EM spectrum can be used to sterilise food and medical equipment? 10. What medical procedure can gamma rays be used for? 11. What is the medical use of X-rays? 12. Name two uses of infra red: 13. Why are radio waves so useful to long distance communication. 14. Starting with the longest wavelength name the order of the ‘visible spectrum’

ANSWERS 1.Radio waves 2.Gamma Waves 3.Gamma Waves 4.Radio Waves 5.All EM waves: are transverse, can travel through a vacuum, all travel through space at the speed of light. 6.Shorter wavelength (higher frequency) more dangerous. 7.Microwaves

CONTINUED 8.Ultra Violet 9.Gamma 10.To kill cancer. 11.Check bones and teeth. 12.Remote controls and thermograms 13.Diffraction over hills and between buildings. Reflected by the ionosphere 14.Red, orange, yellow, green, blue, indigo, violet