Light 1: Flashcards
What is light?
Light is a form of energy
How does light travel
In straight lines
Describe the law of refraction
The law of reflection is that the angle of incidence is the same as the angle of reflection.
What is the normal?
All angles are measured from the normal. The normal is a line at to the object.
Define refraction
The bending of light
What happens to light as it goes from one material to another…. why does this happen?
Light changes direction as light goes from one material into another because its speed changes as the density of the material changes. e.g. Moving from glass to air.
Describe a convex lens
It is thick in the middle and thin at the edges.
What happens when light passes through a convex lens?
A convex lens causes the light rays to converge (come together).
Define focus (focal point)
When a convex lens causes the light rays to converge, the point where the rays meet is called the focus.
What happens when we compare a thick convex lens to a thinner one
A thick convex lens brings the focal point closer.
The thicker the lens the closer it will be.
What do we use convex lenses for in glasses
Convex lenses are used in eyeglasses for correcting farsightedness (long sighted).
Glasses with convex lenses increase refraction, and accordingly reduce the focal length.
Describe the shape of a concave lens
A concave lens is thin in the middle and thick at the edges
Remember caves go in!
What happens when light passes through a concave lens?
A concave lens causes the light rays to diverge converge (move further apart).
How could we help a person who is short sighted?
Use concave lenses in their glasses to to correct short sight.
A short sighted person’s focus is focusing before the back of the eyeball. The concave lens pushes the rays of light further apart so that they arrive together in proper focus at the back of the eye.
Which lens have the greatest refraction?
The more curved a lens is the greater the refraction
