JAMB - Physics (2003 - No. 33)
A ray incident on a glass prism undergoes minimum deviation when the
incident angle is equal to the angle of refraction
refraction angle equals 90o
incident angle equals 90o
incident angle is equal to the angle of emergence
Paliwanag
At minimum deviation, it is observed that light passes symmetrically through, the prism such that the angle of incidence (io) is angle to the angle of emergency (eo).(i/e Io = eo)