1. Science A Physics – P1 Science A Physics – P1 Topic 5b : Electromagnetic Spectrum Topic 5b : Electromagnetic Spectrum

2. There are seven types of electromagnetic wave which form the electromagnetic spectrum (EMS). The spectrum extends from long wavelength, low frequency radio waves to short wavelength, high frequency gamma rays. Wavelength

3. The Sun produces solar radiation which contains different forms of electromagnetic radiation, e.g. visible light, ultraviolet, infra red. Solar Radiation

4. Only a tiny portion of the Sun’s massive energy ever reaches the Earth. However, that tiny portion is more than enough to support life on Earth and drive the weather systems. A Thermal Image of a Solar Flare

5. This thermal image shows the temperature of the oceans. It can be seen that the equator receives the greatest incidence of solar energy. This has significant consequences for the various ecosystems and weather systems of the planet. The Fate of Solar Energy When a substance absorbs radiation, the energy carried by the radiation causes it to become hotter.

6. Properties of Electromagnetic Waves  Can be reflected, refracted or diffracted. All electromagnetic waves:  Are transverse waves.  Transfer energy from one place to another.  Can travel through a vacuum.  Travel at the same speed. The speed of light in a vacuum is 300,000,000m/s.  Consist of oscillating electric and magnetic fields.

7. The Electromagnetic Spectrum

8. Electromagnetic waves obey the wave formula: Wave Equation (metre/second, m/s)(Hertz, Hz)(metre, m) Frequency (f)x Wavelength ( ) =Wave Speed (v) However: i. all electromagnetic waves have the same wave speed, so that in the diagram above the waves with the shortest wavelength have the highest frequency. ii. the values of speed, frequency and wavelength cover a wide range of values from very very small to very very big, and this means that we need to use a special mathematical notation for these numbers. It is called standard form. For example the speed of 300 000 000 m/s is now written as 3 x 10 8 m/s.

9. Now complete the Standard Form Worksheet.

10. Electromagnetic waves obey the wave formula: Wave Equation (metre/second, m/s)(Hertz, Hz)(metre, m) Frequency (f)x Wavelength ( ) =Wave Speed (v) Point the cursor over the formula triangle to show the 3 formulas... (v) (f) ( )

11. Electromagnetic waves obey the wave formula: Wave Equation Point the cursor over the formula triangle to show the 3 formulas... (metre/second, m/s)(Hertz, Hz)(metre, m) Frequency (f)x Wavelength ( ) =Wave Speed (v) (v) (f) ( )

12. A microwave oven uses waves that have: Calculate the frequency... f = v f =300,000,000m/s 0.12m f =2,500,000,000 f =2,500MHz (1MHz = 1,000,000Hz) Using the Wave Equation  A wavelength of 0.12m  A speed of 300,000,000m/s

13. A DVD remote control gives of Infra Red radiation of frequency 10 14 Hz. Calculate the wavelength. Calculate the frequency... f = v λ = 300,000,000 m/s 10 14 m λ =3 x 10 -8 m Using the Wave Equation

14. An X-ray photograph is taken with e-m waves that have: Calculate the frequency... f = v f = 3 x 10 8 m/s 4 x 10 -9 m f =7.5 x 10 16 Hz Using the Wave Equation  A wavelength of 4 x 10 -9 m  A speed of 3 x 10 8 m/s

15. How Many Applications of EMS Do You Know? Drag the application to the correct box...