How lenses work Flashcards
1
Q
What do lenses do
A
- Lenses focus and disperse light using refraction-
2
Q
What is a convex lens
A
- Refracts parallel rays of light inwards to a single point (known as the focal point)
- Also known as a converging lens
3
Q
What is a concave lens
A
- Refract parallel rays of light outwards (disperse the light)
- We trace virtual lines from the focul point to the point where the rays hit the lens. If we carry these lines on then we get the direction that the light was dispersed in
4
Q
Explain the focul point
A
- All lenses have a focul point on both sides
- The focul point is always equal distance from the center
- The focul point always sits on the axis (a line passing through the middle of the lens)
- The distance between the lens and the focul point is known as the focul length
5
Q
What affects the focul length
A
- The shorter the focul length, the more powerful the lens
6
Q
How to make a lens more powerful
A
- Make the lens more curved
- Use a different material that naturally refracts light more powerfully
7
Q
How is an image formed
A
- An image is formed at points where all light rays from a particular point on an object appear to come together
8
Q
What is a real image
A
- Light rays actually come together to form the image (E.G: the eye)
9
Q
What is a virtual image
A
-Light rays don’t come together where the image appears to be (E.G: mirror)
