1: Exam Questions

Question 1

Calculate n (refractive index), given 2 values: speed of light in vacuum and speed of light in another material

Answer 1

Refractive Index = c/v

Question 2

Describe the effect of the lens on the wavefronts (convex)

Answer 2

Adds curvature to wavefronts

Question 3

Explain how the lens produces the effect (parallel beam of light passing through convex lens)

Answer 3

1) Lens thinner at edges, 2) So waves slowed for less time

Question 4

Explain how the higher refractive index can be less heavy than the thick lens

Answer 4

mass = ρV and 2nd lens has less volume

Question 5

Explain how the higher refractive index can have the same power as the thick lens

Answer 5

higher n means greater slowing/bending of light so thinner lens is needed

Question 6

How does the diagram (normal waves approaching convex lens) show that the object is very distant from the lens?

Answer 6

wavefronts are plane / flat / not curved