KS3 Science. Light and Sound

Transcription

1 KS3 Science Light and Sound

2 Light and Sound Key Words Write a definition for each of the key words listed below Key words Frequency Wavelength Amplitude Reflection Refraction Dispersion Light Spectrum Vacuum 2

3 1. Light Fill in the missing words 1. Light travels in s. Lines 2. Light travels as a type of electromagnetic R.. 3. Light travels at a speed that is much F than that of sound 4. Some things can be seen through. They are said to be T.. 5. Some things don't let light through at all. These are called O materials 6. Some things give out their own light. These are said to be L. 7. All other things we see because they R. Light 8. For use to see something, light must enter our E. Look at the diagram below: screen light source object 1. Continue the two light rays to show where they would hit the screen 2. On the screen draw the shadow that the heart would form 3. Put an arrow onto each ray, to show which way the light is travelling 4. Imagine that you had a pinhole camera where the screen is. Draw the shape that would form on t he small screen inside the camera in the space below. 3

4 2. Reflection Follow the instructions below. Label the straight line drawn below as MIRROR Draw a line from the middle of the mirror at right angles to it. Label this line with its correct name. Draw a ray of light hitting the mirror where the two lines join. The angle between the ay and the mirror should be 40 degrees. Label the angle of incidence and write what its value is Draw in the reflected ray Label the angle of reflection and say what its value is ANGLE OF INCIDENCE = 4

5 3. Refraction 1. Complete these sentences by circling the correct word in brackets: When light is travelling through a medium it travels in a (straight/curved) line. When light moves from one medium into another, its speed (isn t/is) changed. In the new medium it continues to travel in a (curved/straight) line, but with a new direction. This change happens because the speed of light is (the same/different) in different materials. The name given to this effect is (reflection/deflection/refraction). 2. Complete the diagrams to show the path taken by the ray of light from air to glass and from glass to air. 3. Complete the following sentences by circling the correct words in brackets When light moves from air to glass it will bend (Away from/towards) the normal When it moves from glass to air it will bend (away from/towards) the normal If the light s travelling along the normal its direction (will/will not) be changed. 5

6 4. Dispersion Fill in the gaps using the words below: PRISM BENT WHITE RAINBOWS SPECTRUM SLOWS DOWN SPLITS UP When light goes through a prism it into all the colours of the rainbow. This is called a. White light is made up of a mixture of colours. Each of these colours is refracted ( ) different amounts by the because they different amounts when they get to the glass. This is how we get. 1. Label the diagram using the words below: Ray of white light Prism A spectrum 2. Colour in the spectrum remember red light bends the least, violet bends the most. Write down the names of the colours next to the spectrum. 3. Write down your way of remembering the order of the colours of a spectrum (red to violet). 4. Explain why white light splits up into the different colours when it goes through a prism. 5. There are three primary colours of light. They are red, green and blue. All the other colours of the spectrum are mixtures of these colours. What two primary colours of light do you think makes up: a) Yellow light? b) Violet light? c) Cyan (pale blue) light? 6

7 5. The Eye Label the diagram using the information from the table below. Fill in the table giving the function of each of the structures listed Structure Pupil Function Iris Cornea Retina Lens Optic nerve 7

8 6. Sound Vibrations Fill in the blanks: 1. The propagation of sound can be described in terms of motion of a 2. Sound cannot travel through a.. 3. Sound can travel through gases,. And.. 4. A high of vibrations makes a pitched sound. 5. A large of vibrations makes a sound. 6. Sound travels quickly than light. 7. We hear sound when a sound wave causes our.. To vibrate. 8. Some sounds have too a frequency to hear. Look at the images below: 1. Which sounds have a higher frequency than A? 2. Which sounds have a lower frequency than A? 3. Which sounds all have the same pitch? 4. Which sounds are louder than A? 5. Which sound has a higher pitch than A, but is at the same volume? 6. How would sound D compare to sound A. 8

9 7. The Ear Label the parts of the ear using the key words below: AUDITORY CANAL AUDITORY NERVE EAR DRUM COCHLEA OUTER EAR Answer the following questions 1. What is the job of the outer part of the ear? 2. What is the job of the ear canal?.. 3. The ear can often get blocked with wax. What effect does this have on hearing? 4. Explain how we hear sounds 9

10 Summary Questions Answer the summary questions 1. Which travels faster: light or sound? 2. Name on thing that sound can t travel through 3. What determines the pitch of a sound? 4. What happens to the ear drum when sound waves hit it? 5. What part of the ear generates electrical signals to send to the brain? 6. What is the law of reflection? 7. What is refraction? 8. How could you show that white light is not just one colour? 9. Why does your school blazer look green in white light? 10

11 Summary Questions Answer the summary questions 10. What happens to the colours of white light when they hit something black? 11. What colour would green laces look in red light and why? 12. What does sound need to travel from one place to another 13. Why couldn t you hear a ringing bell in a vacuum? 14. Does sound usually travel fast in solids, liquids or gases? Explain your answer. 15. What does the frequency of a sound mean? 11