Year 8 Light and Sound

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Year 8 Light & Sound Learning Objectives

Pupils should know:

1.         that light travels at different speeds in different media 

2.         that the speed depends upon the optical density of the medium 

3.         that light changes speed when it goes from one substance to another and this causes the light to change direction 

4.         that a normal is a line drawn at 90 to the surface at the point light strikes 

5.         that when light enters an optically more dense medium it slows down, causing it to bend towards the normal 

6.         that when light enters an optically less dense medium it speeds up, causing it to bend away from the normal 

7.         that the bending of light is called refraction 

8.         how to use refraction to explain some phenomena such as apparent depth 

9.         how total internal reflection occurs 

10.       that the critical angle is the angle which if exceeded total internal reflection will occur 

11.       some uses of total internal reflection 

12.       how to explain refraction using the wave model 

13.       that a loud sound is produced by a large vibration and vice versa 

14.       that a high pitched sound is produced by a very frequent (quick) vibration and vice versa 

15.       that an microphone can change sound to electricity and that this can then be displayed on an oscilloscope 

16.       that the wave displayed on an oscilloscope is a transverse wave 

17.       how to identify the amplitude, the wavelength and the frequency of a wave 

18.       recognise the link between the loudness of the sound and the amplitude of the wave 

19.       recognise the link between the pitch of the sound and the frequency/wavelength of the wave 

20.       how to use: speed of wave = frequency x wavelength 

21.       that an echo is produced when sound is reflected from a hard, flat surface 

22.       how to calculate the distance to an object from the time delay of the echo

23.        that white light can be split to produce a spectrum of colours 

24.        that this is called dispersion 

25.        that it occurs because the colours have different wavelength and therefore      change speed  by different amounts 

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