User interface language: English | Español

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 Calculate 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 ff of the lens.

Draw on the diagram the three wavefronts after they have passed through the lens.

[2]
a.

Lens A has a focal length of 4.00cm4.00cm. An object is placed 4.50cm4.50cm to the left of A. Show by calculation that a screen should be placed about 0.4m0.4m from A to display a focused image.

[2]
b.

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 2.00cm2.00cm and the final real image is 8.00cm8.00cm from the lens. Calculate the distance between lens A and lens B.

[3]
c.

Calculate the total magnification of the object by the lens combination.

[2]
d.

Markscheme

wavefront separation identical and equal to separation before the lens

wavefronts converging, approximately centered on ff

 

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. 

a.

1v=14.00-14.501v=14.0014.50 ✓

v=36.0 «cm» ✓

 

b.

A:1-2.0=18+1u ✓

u=-1.6 «cm»  ✓

distance necessary = «36.0-1.6=»34.4 «cm»

 

Allow [2 max] for ECF for no negative in MP1. Gives u=2.7 and distance of 38.7«cm»

Allow ECF from (b) in MP3.EG use of 0.4m/40cm.

c.

«m=-io=-364.5  for A or -8-1.6 for B»

mA=«»8  OR  mB=«+»5 ✓

total magnification =«» 40 ✓

 

Allow [2] marks for a bald correct answer

Allow ECF from (b) and (c).

Eg if u=2.7cm in (c) then mB=3 and total m=24

d.

Examiners report

[N/A]
a.
[N/A]
b.
[N/A]
c.
[N/A]
d.

Syllabus sections

Option C: Imaging » Option C: Imaging (Core topics) » C.1 – Introduction to imaging
Show 51 related questions
Option C: Imaging » Option C: Imaging (Core topics)
Option C: Imaging

View options