Ans. REFRACTION THROUGH LENSES
1.In lenses image is formed through refraction of light. Image formation in convex lens can be explained with the help of three principal rays as shown in the figure given below
The ray parallel to the principal axis passes through the focal point after remains by the lens.
2. The ray passing through the optical centre passes through the lens and passes undeviated.
3. The ray passing through the focal point becomes parallel to the principal axis after refraction by the lens.