Light Flashcards
What does Refraction mean
It causes the light to change speed and this can also cause a change in direction. when light travels from materiel into another.
What happens when light enters at an angle through the normal line.
it refracts and moves towards the normal. When it leaves, it moves away from the normal.
what are two types of lenses
Convex and concave.
convex is out way and concave in way.
what is the name of the distance between a lens and a clear sharp image called
focal length
focal image
how do you measure the focal length
Move the lens back and forth until you see a clear, sharp image of the distant object (window) on the paper. Measure the distance between the lens and the paper.
This is called the focal length of the lens.
what happens when the lens is fat
The ‘fatter’ a convex lens is the shorter the focal length is.
It is more powerful.
what is the formula for the power of a lens
Power of a lens is given by;
Power = ______1______
Focal length
what are the signs given for a convex and a concave lens in a glasses
A positive sign (+) is used for a convex lens and a negative sign (-) is used for a concave lens.
what lens are good for a shortsighted and a longsighted
shortsighted= concave so the light ray will spread out before entering longsighted= convex so the light rays will focus on the retina.
what are laser
A laser is a narrow beam of concentrated light of only one colour (not white)
Lasers can be used in medicine for…..
- Laser eye surgery
- Vaporising tumours
- Tattoo/birth mark removal
Why does a pencil sitting in a beaker of water appear to be bent?
because the light that is reflected to the surface of the water is the refracted to our eye but our eye thinks that the pencil in much father away or much shallower.
like a stone in the sea and you try to pick it up but it much father away.
Why do the jelly spheres seem to disappear in water
If two materials have the same refractive index (n for jelly spheres and water are both about 1.3) then it is very difficult for our eyes to tell when one is inside the other.
How does a prism split white light into the visible spectrum?
when white light enters the prism it gives out the full septrum this is because each of the colours in the septrum is refracted at different angles
red light is refracted the least and violet is refracted the most because it is more towards the angle of refraction.
what lens can be used to produce images of objects
convex
