Prism-A prism is a wedge shaped portion of a transparent refracting medium bounded by two plane faces inclined to each other at an angle.

1. Refracting faces- The two plane faces of prism which inclined to each other are called the refracting faces.

2. Angle of prism- The angle included between the two refracting faces is called the angle of prism.

3. Principal section- The section of the prism cut by a plane perpendicular to refracting edge is the principal section of the prism.

4.-Refracting edge- The line along which the two refracting faces meet is the refracting edge of prism.

5. Base of prism-The face of the prism which is opposite to the refracting edge is the base of the prism.