Physics

Mara

21 November, 17:08

A ray of light is incident on an unknown transparent substance from

of incidence is 40°, and the angle of refraction is 22°

(a) Explain why these measurements indicate that a change in speed must be happening as the light changes medium. Qualitatively justify whether the speed of

light in the unknown transparent substance is higher or lower than that of air.

(b) Calculate the absolute index of refraction for this substance. Calculate the velocity of light in this substance.

(c) The substance is now submerged in glycerol (n = 1.47). Calculate the critical angle of incidence for light going from the unknown substance into glycerol. Explain why there is no critical angle when going the other way, from glycerol into the substance.

(d) The substance is now shaped into a convex lens. How does the focal length of this lens compare with the focal length of a similar-shaped lens made out of crown glass (n = 1.52) ? Justify your answer.