Question

list the sign convention that are followed in case of refraction of light through spherical lenses. Draw a diagram and apply these convention in determining the nature and focal length of a spherical lens which forms three times magnified real image of an object placed 16 cm from the lens​

Answer 1

The following sign convention is used for measuring various distances in the ray diagrams of spherical mirrors:

Object is always placed to the left of mirror

All distances are measured from the pole of the mirror.

Distances measured in the direction of the incident ray are positive and the distances measured in the direction opposite to that of the incident rays are negative.

Distances measured along y-axis above the principal axis are positive and that measured along y-axis below the principal axis are negative.

Since the image formed is magnified and virtual, the mirror is convex.