Optics (Module 5)

Question 1

Does the light ray bend towards or away from the normal when going from air to glass?

Answer 1

The light ray bends towards the normal when going from air to glass

Question 2

What does i, r, and n mean in the equation n=sin i/sin r?

Answer 2

i=Angle of incidence
r=Angle of refraction
n=Refractive index

Question 3

Define the critical angle

Answer 3

The angle which causes light to travel along the boundary of the glass when travelling from glass to air

Question 4

Explain total internal refraction stating the two requirements for it to occur

Answer 4

Total internal refraction is where the light entering a substance is at an angle greater than the critical angle so that the ray refracts back like a mirror rather than leaving the substance. In general, this can only occur if:

• The incident substance has a larger refractive index than the other substance
• The angle of incidence exceeds the critical angle