Question | Answer |
periscope experiment. | position your eye as indicated in the diagram.light from a distant source hits the upper mirror.this light reflects to the lower mirror and then reflects into your eye. the operation of the periscope has been demonstrated. |
what is the main purpose of the periscope? | to see over obstacles. |
how does a periscope work? | light from a distant object being reflected in the upper mirror. this light falls to the lower mirror and is relected again into the eye. the mirrors are set at 45 degrees to enable this reflection to occur. |
why do submarines use periscopes? | they use periscopes to gain sight of vessels on the water surface. |
an example of refraction is... | a pencil in water. |
what is refraction? | refraction of light is the bending of light as it passes from one medium to another. |
refraction from air to glass and glass to air. | u can c d lite beam on d paper as it head 4 d glass block.d lite bends as it enters d glass. d lite bends as it leaves d glass block. remember which way d lite bends as it enters and leaves d glass. |
applications of refraction. | telescopes, microscopes, prisms, contact lenses. |
application of lenses. | far sighted- converging convex lens.
near sighted- diverging concave lens. |
what is light? | light is a form of energy that is got from the sun. it travels extremely fast. its euation is 3x10 ( 2 d power of 8) ms ( to d power of -1) |
experiment: to show that light travels in straight lines. | equipment: a bulb and 3 pieces of cardboard.
method: take 3 similar pieces of cardboard.
put a hole in d exact centre of each of them.
place d 3 pieces of cardboard between ur eye and d bulb.
result: u will c d light if d holes r in a straight line. |
how does light travel? | it travels in a straight line. |
why is light a form of energy? | as it can make things move. |
why are shadows formed? | as light travels in straight lines and light cannot pass through certain materials e.g. opaque materials. |
what are luminous objetcs? | objects that give out light. eg a candle. |
what are non luminuous objects? | objects that dont give out light but refelct light from luminuous objects. e.g. the moon. |
what is dispersion? | the breaking up of white light into its component colours. red orange yellow green blue indigo violet. |