Date | November 2019 | Marks available | 1 | Reference code | 19N.3.SL.TZ0.7 |
Level | Standard level | Paper | Paper 3 | Time zone | 0 - no time zone |
Command term | Sketch | Question number | 7 | Adapted from | N/A |
Question
The diagram, drawn to scale, shows an object O placed in front of a converging mirror. The focal point of the mirror is labelled F.
A planar wavefront of white light, labelled A, is incident on a converging lens. Point P is on the surface of the lens and the principal axis. The blue component of the transmitted wavefront, labelled B, is passing through point P.
Construct a ray diagram in order to locate the position of the image formed by the mirror. Label the image .
Estimate the linear magnification of the image.
Describe two features of the image.
Sketch, on the diagram, the wavefront of red light passing through point P. Label this wavefront R.
Explain chromatic aberration, with reference to your diagram in (b)(i).
An achromatic doublet reduces the effect of chromatic aberration. Describe an achromatic doublet.
Markscheme
correctly draws any 2 of the 4 conventional rays from the object tip ✔
correctly extends reflections to form virtual upright image in approximate position shown ✔
NOTE: No ECF for incorrect rays in MP1.
Award [0] for rays of converging lens or diverging mirror.
1.5 ✔
NOTE: For “correct” image position in (a)(i) allow 1.3 to 1.7
Any two of:
virtual OR upright OR larger than the object ✔
“circular” wave front through P: symmetric about the principal axis AND of greater radius than B ✔
red and blue wave fronts have different curvature/radius
OR
red and blue waves are refracted differently/have different speeds ✔
so different colors have different foci/do not focus to one point
OR
so image is multi-coloured/blurred ✔
NOTE: MP1 is for the reason for the aberration, MP2 is for the effect.
mention combination of converging and diverging lenses ✔
of different refractive index/material ✔
NOTE: Achromatic doublet is in the question, so no marks for mentioning this.