1. Physics 1 Revision Lesson 6 Sound and the Red shift

2. Sound

3. Sound is a longitudinal wave Sound waves cause vibrations in a medium, which are detected as sound direction of wave

4. The pitch of a sound is determined by its frequency and loudness by its amplitude.

5. Echoes are reflections of sounds

6. Red Shift

7. As the police car moves away from the standing girl, the sound of the siren changes. This is because the wavelength and frequency of the waves changes as the police car drives away. This is called the Doppler effect

8. If a star or galaxy is moving towards us, the light waves it gives off are high in frequency If a star or galaxy is moving away from us, the light waves it gives off are low in frequency. High frequency light waves are blue in colour and low frequency light waves are red in colour

9. The further away a galaxy is, the more the light is shifted towards the red spectrum. This means that the light from the galaxy must be moving away from us, and therefore the whole galaxy must be moving away from us. This is called red shift G G G Red shift!

10. The big bang theory All matter starts from a single initial point A massive explosion sends matter outwards Causing universe to expand Massive explosion Single initial point

11. Scientists have also detected cosmic microwave background radiation. This is received from all parts of the Universe and is thought to be the heat left over from the original explosion.

12. Key words and statements

13. Blue shift Big bang theory Cosmic microwave background radiation Echoes Red shift Sound waves Doppler effect Are reflections of sound waves Galaxies moving away from us emit light (long wavelength) shifted towards the red spectrum Galaxies moving towards us emit light (short wavelength) shifted towards the blue spectrum Left over radiation from the big bang Are longitudinal waves which vibrate the particles in the air. We hear this as sound As sound moves away or towards you the frequency and wavelength changes. you hear this as a change of tone A theory that states the universe began with a single point explosion and is expanding Sound and the Red shift

14. Blue shift Big bang theory Cosmic microwave background radiation Echoes Red shift Sound waves Doppler effect Are reflections of sound waves Galaxies moving away from us emit light (long wavelength) shifted towards the red spectrum Galaxies moving towards us emit light (short wavelength) shifted towards the blue spectrum Left over radiation from the big bang Are longitudinal waves which vibrate the particles in the air. We hear this as sound As sound moves away or towards you the frequency and wavelength changes. you hear this as a change of tone A theory that states the universe began with a single point explosion and is expanding Sound and the Red shift

15. If a star or galaxy is moving away from us… The further away a galaxy is… The big bang theory is supported by… As the police car moves away from the standing girl, the sound of the siren changes. This is because … If a star or galaxy is moving towards us… The higher the amplitude… The higher the frequency… the wavelength and frequency of the waves changes as the police car drives away the more the light is shifted towards the red spectrum the light waves it gives off are high in frequency Red shift and cosmic microwave background radiation The louder the sound The more high pitch the sound the light waves it gives off are low in frequency. Sound and the Red shift

16. If a star or galaxy is moving away from us… The further away a galaxy is… The big bang theory is supported by… As the police car moves away from the standing girl, the sound of the siren changes. This is because … If a star or galaxy is moving towards us… The higher the amplitude… The higher the frequency… the wavelength and frequency of the waves changes as the police car drives away the more the light is shifted towards the red spectrum the light waves it gives off are high in frequency Red shift and cosmic microwave background radiation The louder the sound The more high pitch the sound the light waves it gives off are low in frequency. Sound and the Red shift