| Date | May 2011 | Marks available | 6 | Reference code | 11M.3.SL.TZ1.20 |
| Level | Standard level | Paper | Paper 3 | Time zone | Time zone 1 |
| Command term | Define, Explain, and Label | Question number | 20 | Adapted from | N/A |
Question
This question is about a convex lens.
The diagram below, drawn to scale, shows a small object O placed in front of a thin convex (converging) lens. The focal points of the lens are shown, labelled F. The lens is represented by the straight line XY.
(i) Define the term focal point.
(ii) On the diagram above, construct the paths of two rays in order to locate the position of the image formed by the lens. Label the image I.
iii) Explain whether the image is real or virtual.
Markscheme
(i) the point on the principal axis;
through which parallel rays pass after going through the lens / from which rays are parallel after passing through the lens;
(ii) 
any two correct rays out of the three shown above;
image correctly located and labelled;
(iii) virtual because no rays pass through the image / image cannot be formed on a screen;
Mark is for explanation, not for statement of virtual.
