Geometrical construction for refracted ray

Geometrical construction for refracted ray

The alternative method of treating the results of the last experiment suggests a way of finding the path of a ray through a glass block or some other medium, when i and n are given.

Example. Trace the path of a ray through a glass block of refractive index 1.52, for light entering at an angle of incidence of 45°. Measure the angle of refraction.

Geometrical construction for refracted ray
Geometrical construction for refracted ray

Draw SS’ to represent the surface of separation between glass and air and AO an incident ray making an angle of 45° with the normal NO (Fig. 23.5). Then, using the largest possible scale for best accuracy, mark off OD equal to 1.52 units of length. At D erect a perpendicular to cut AO at B. With centre 0 and radius OB, draw a circle. Along OS’, mark off OE equal to I unit of length. Through E draw a perpendicular to SS’ to cut the circle at C. Then OC is the required refracted ray and the angle of refraction r is found to be 28°.

Geometrical construction for refracted ray
Geometrical construction for refracted ray
Share This