Question

State the sign convention to measure the distances for a lens.

Answer 1

1. Every distance is measured starting at the optical centre.
2. The object should be positioned to the left of the lens. It measures the object's distance, i.e., u.
3. f stands for the second focus, also known as the focal length, and v stands for the image distance.

4. Distances measured with respect to the incoming ray's direction are recorded as positive, while those measured in its opposite direction are recorded as negative. That is, distances marked as +ve to the right and -ve to the left of the lens.

5. +ve and -ve stand for height or length above the major axis, respectively.