Question

Describe the New Cartesian Sign Convention used in optics. Draw a labelled diagram to illustrate this sign convention.

Answer 1

For measuring the various distances in the ray diagrams of reflection by spherical mirrors, we shall adopt the following system of signs called new cartesian sign conventions.

1. All the distances in a ray diagram of reflection by spherical mirrors are measured from the pole of the spherical mirror.


2. The distances measured in the direction of incident light are taken as positive.


3. The distances measured in the direction opposite to the direction of incident light are taken as negative.


4. The heights measured upwards and perpendiculars to the principal axis of the mirror are taken as positive.


5. The heights measured downwards and perpendiculars to the principal axis of the mirror are taken as negative.