Question

According to Cartesian sign convention, in ray optics:

• A. All distances in the direction of incident ray are taken positive
• B. All distances are taken negative
• C. All distances in the direction of incident ray are taken negative
• D. All distances are taken positive

Answer 1

Answer: (A)

All distances in the direction of incident ray are taken positive

All the distance are measured from the optical center. The distances measured in the direction of incident rays are positive and all the distances measured in the direction opposite to that of the incident rays are negative.