How lenses work

Question 1

What do lenses do

Answer 1

• Lenses focus and disperse light using refraction-

Question 2

What is a convex lens

Answer 2

• Refracts parallel rays of light inwards to a single point (known as the focal point)
• Also known as a converging lens

Question 3

What is a concave lens

Answer 3

• 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

Question 4

Explain the focul point

Answer 4

• 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

Question 5

What affects the focul length

Answer 5

• The shorter the focul length, the more powerful the lens

Question 6

How to make a lens more powerful

Answer 6

• Make the lens more curved
• Use a different material that naturally refracts light more powerfully

Question 7

How is an image formed

Answer 7

• An image is formed at points where all light rays from a particular point on an object appear to come together

Question 8

What is a real image

Answer 8

• Light rays actually come together to form the image (E.G: the eye)

Question 9

What is a virtual image

Answer 9

-Light rays don’t come together where the image appears to be (E.G: mirror)