Glancing angle `theta` is equal to (where, I is angle of incidence and r is angle of refraction )

Define angle of incidence and angle of refraction.

If the angle of incidence is 0^(@) , the angle of refraction is 90^(@) .

The ratio of sine of angle of incidence to the sine of angle of refraction.

What is meant by the 'angle of incidence' and the 'angle of refraction' for a ray of light? Draw a labelled ray diagram to show the angle of incidence and the angle of refraction for a refracted ray of light.

Draw diagrams to show the refraction of light from (i) air to glass, and (ii) glass to air. In each diagram, label the incident ray, refracted ray, the angle of incidence (i) and the angle of refraction (r).

Angle of incidence for which the angle of refraction becomes 90^(@)