Date | November 2020 | Marks available | 2 | Reference code | 20N.3.SL.TZ0.11 |
Level | Standard level | Paper | Paper 3 | Time zone | 0 - no time zone |
Command term | Draw | Question number | 11 | Adapted from | N/A |
Question
A beam of monochromatic light from infinity is incident on a converging lens A. The diagram shows three wavefronts of the light and the focal point f of the lens.
Draw on the diagram the three wavefronts after they have passed through the lens.
Lens A has a focal length of 4.00 cm. An object is placed 4.50 cm to the left of A. Show by calculation that a screen should be placed about 0.4 m from A to display a focused image.
The screen is removed and the image is used as the object for a second diverging lens B, to form a final image. Lens B has a focal length of 2.00 cm and the final real image is 8.00 cm from the lens. Calculate the distance between lens A and lens B.
Calculate the total magnification of the object by the lens combination.
Markscheme
wavefront separation identical and equal to separation before the lens ✓
wavefronts converging, approximately centered on f ✓
By eye.
Dotted construction lines are not required, allow wavefronts to extend beyond or be inside the dotted lines here.
Allow [1 max] if only two wavefronts drawn.
1v=14.00-14.50 ✓
v=36.0 ✓
✓
✓
distance necessary = ✓
Allow [2 max] for ECF for no negative in MP1. Gives and distance of
Allow ECF from (b) in MP3.EG use of .
« for A or for B»
OR ✓
total magnification ✓
Allow [2] marks for a bald correct answer
Allow ECF from (b) and (c).
Eg if in (c) then and total