Give conventions used in lenses. (OR) Write the signs of convex and

1.	Give conventions used in lenses. (OR) Write the signs of convex and concave lens using in drawing ray diagrams.
Answer» 1. All distances are measured from optical centre of the lens. 2. Distances measured along the direction of the incident light are taken as positive. 3. The distances against the incident light are taken as negative. 4. The heights measured vertically above the axis, are taken as positive. 5. The heights measured vertically down the axis, are taken as negative.

Give conventions used in lenses. (OR) Write the signs of convex and concave lens using in drawing ray diagrams.

Answer»

1. All distances are measured from optical centre of the lens.

2. Distances measured along the direction of the incident light are taken as positive.

3. The distances against the incident light are taken as negative.

4. The heights measured vertically above the axis, are taken as positive.

5. The heights measured vertically down the axis, are taken as negative.