KS3 Questions on Sound
Q8. A teacher shines a laser beam onto a classroom window. It reflects off the window and onto a screen.
(a) On the diagram below, continue the laser beam to show its path as it reflects off the window and onto the screen. Use a ruler. Add arrows to show the direction of the laser beam.
![](../light/Lightgraphic8AANS.png)
See diagram
- the angles of incidence and reflection must be equal
![](../../../graphics/symbols/nuclides/ticksmall.png)
- the rays must be continuous and straight with an arrow in the correct direction
![](../../../graphics/symbols/nuclides/ticksmall.png)
2 marks
(b) When a pupil plays her flute in the classroom the window vibrates.
(i) When a pupil plays her flute in the classroom the window vibrates.
Give the reason for this.
The sound waves travel to the window in the form of vibrations of air molecules. ![](../../../graphics/symbols/nuclides/ticksmall.png)
The air molecules near to the window receive the vibration and hit the window thereby passing on on the vibration. ![](../../../graphics/symbols/nuclides/ticksmall.png)
(ii) When the window vibrates, what happens to the laser beam that is reflected off the window?
The beam will vibrate or jump about ![](../../../graphics/symbols/nuclides/ticksmall.png)
3 marks
(c) The teacher places a microphone near the pupil as she plays her flute.
The diagram below shows the pattern on an oscilloscope screen.
![](pic9a.png)
The pupil then plays her flute at a higher pitch and more quietly.
Which diagram below shows the pattern that would be seen on the oscilloscope?
![](pic9.png)
1 mark
maximum 6 marks