Question 19M.3.SL.TZ2.biii
| Date | May 2019 | Marks available | [Maximum mark: 2] | Reference code | 19M.3.SL.TZ2.biii |
| Level | SL | Paper | 3 | Time zone | TZ2 |
| Command term | Outline | Question number | biii | Adapted from | N/A |
A student places an object 5.0 cm from a converging lens of focal length 10.0 cm.
The student mounts the same lens on a ruler and light from a distant object is incident on the lens.
A new object is placed a few meters to the left of the original lens. The student adjusts spacing of the lenses to form a virtual image at infinity of the new object. Outline, without calculation, the required change to the lens separation.
[2]
image formed by 10 cm lens is greater than 10 cm/further to the right of the first lens ✔
so second lens must also move to the right OR lens separation increases ✔
Award [1 max] for bald “separation increases”.
Many candidates did not read the question carefully and provided totally incorrect answers. It does not seem to be generally well known that if a distant object is moved to the right, for a converging lens, then the real image must also move to the right.
