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Year 8 Light
revision for the Year 8 test
| Question | Answer |
|---|---|
| What is the incident ray? | The incoming ray. |
| What is the reflected ray? | This is the outgoing ray. |
| What is the normal line? | This is at right angles to the surface and from which angles are measured. |
| What is the angle of reflection? | This is the angle between the normal and the reflected ray. |
| What is the angle of incidence? | This is the angle between the normal and the incident ray. |
| Define refraction. | This is the change in direction of light going from one material to another. |
| What is the meaning of 'absorption'? | This is when energy is transferred from light to a material. |
| What is scattering of light? | This is when light bounces off an object in all directions. |
| Define 'transparent' material. | This is material that allows all light to pass through it. |
| What is translucent material. | A material that allows some light to pass through it. |
| What is opaque material? | Material that allows no light to pass through it. |
| Describe a convex lens. | A lens that is thicker in the middle which bends light rays towards each other. |
| Describe a concave lens. | A lens that is thinner in the middle which spreads out light rays. |
| What is the retina? | The layer at the back of the eye with light detecting cells and where an image is formed. |
| How fast does light travel? | Light travels at 300 million metres per second in a vacuum. |
| What happens when light enters a denser material, for example, a clear Perspex block. | It bends towards the normal. |
| What happens when light enters a less dense material, for example, going from a clear Perspex block into air> | It bends away from the normal. |
| What does the angle of incidence equal? | The angle of reflection. |
| What does light travel in? | Straight lines. |
| What happens when you shine light into a prism at an angle? | It separates into the colours of a rainbow. |
| What is a luminous source? | This is an object that can create light. |
| What is a non-luminous object. | An object that does not create light. |
| How can we see non luminous objects? | We see them because of the light reflected off of them. |
| What is bioluminescence? | This is where organisms are able to create their own light. |
| What is reflection? | When a wave hits a solid object it’s energy is reflected back the way it came. If this is light we see a reflection either of light or an image |
| What is specular reflection? | This is the mirror-like reflection of waves, such as light, from a surface. Every ray of light is reflected at the same angle. |
| Explain diffuse reflection. | With diffuse reflection, because the surface is not totally flat the rays of light bounce off in all directions so no clear picture can be formed. |
| What is the law of reflection? | The angle of incidence is equal to the angle of reflection |
| In someone with clear vision, where does light focus? | Exactly on the retina. |
| In a long sighted person, where does the light focus? | Behind the retina. |
| In a short sighted person, where does the light focus? | Before the retina. |
| How can short sight be corrected? | With a concave lens. |
| How can long sight be corrected? | With a convex lens. |
| What is white light made up of? | Different colours. |
| What is the spectrum? | The band of colours produced when light is spread out by a prism. |
| Why does a red object look red? | Because it absorbs all the colours in the spectrum except red which it reflects. |
| Why does a black object look black? | Because it absorbs all the colours in white light and doesn't reflect any. |
| What happens to a red object in green light? | It looks black because it absorbs the green light but there is no red light to reflect. |
Created by:
Highcliffe Science
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