F4C6: Light

Question 1

critical angle

Answer 1

the angle of incidence in the optically denser medium for which the angle of refraction, r = 90° at the optically less dense medium

Question 2

refractive index, n

Answer 2

the ratio of the speed of light in vacuum to the speed of light in the medium

Question 3

focal point

Answer 3

a point to which all rays parallel to the principal axis converge / appear to diverge