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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	Show	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.

[2]

a.

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.

[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 $2.00 cm$ and the final real image is $8.00 cm$ 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 $f$ ✓

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.

a.

$\frac{1}{v} = \frac{1}{4.00} - \frac{1}{4.50}$ ✓

$v = 36.0 « cm »$ ✓

b.

$A : \frac{1}{- 2.0} = \frac{1}{8} + \frac{1}{u}$ ✓

$u = - 1.6 « cm »$ ✓

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 $0.4 m / 40 c m$ .

c.

« $m = - \frac{i}{o} = \frac{- 36}{4.5}$ for A or $\frac{- 8}{- 1.6}$ for B»

$m_{A} = « - » 8$ OR $m_{B} = « + » 5$ ✓

total magnification $= « - » 40$ ✓

Allow [2] marks for a bald correct answer

Allow ECF from (b) and (c).

Eg if $u = 2.7 c m$ in (c) then $m_{B} = 3$ 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

17N.3.SL.TZ0.9a.ii: State the maximum possible distance from an object to the lens in order for the lens to...
17N.3.SL.TZ0.9c.i: On the diagram, draw two rays to locate the point Q′ on the image that corresponds to point Q...
17N.3.SL.TZ0.9c.iv: The screen is now correctly positioned to form a focused image of point R. However, the top...
17N.3.SL.TZ0.9b.ii: State three characteristics of the image.
17N.3.SL.TZ0.9c.iii: A screen is positioned to form a focused image of point Q. State the direction, relative to...
18M.3.SL.TZ2.9a:
Identify, with the letter X, the position of the focus of the primary mirror.
18M.3.SL.TZ2.8b:
The diagram shows an incomplete ray diagram which consists of a red ray of light and a blue ray of light which are incident on a converging glass lens. In this glass lens the refractive index for blue light is greater than the refractive index for red light.

Using the diagram, outline the phenomenon of chromatic aberration.
17N.3.SL.TZ0.9a.i: Sketch a ray diagram to show how the magnifying glass produces an upright image.
17N.3.SL.TZ0.9c.ii: Calculate the vertical distance of point Q′ from the principal axis.
16N.3.SL.TZ0.12d: The lens is moved to a second position where the image on the screen is again focused. The...
18M.3.SL.TZ2.8a.i:
determine the focal length of the lens.
18M.3.SL.TZ1.8a.iii:
Light passing through this lens is subject to chromatic aberration. Discuss the effect that chromatic aberration has on the image formed on the screen.
18M.3.SL.TZ2.8a.ii:
calculate the linear magnification.
16N.3.SL.TZ0.11a: A ray of light is incident on a converging mirror. On the diagram, draw the reflection of the...
17M.3.SL.TZ2.8a.i:
On the diagram, sketch the part of wavefront X that is inside the lens.
18N.3.SL.TZ0.8a: On the diagram, draw lines to show the rays after they have refracted through the lens. Label...
18M.3.SL.TZ1.8b:
A system consisting of a converging lens of focal length F₁ (lens 1) and a diverging lens (lens 2) are used to obtain the image of an object as shown on the scaled diagram. The focal length of lens 1 (F₁) is 30 cm.

Determine, using the ray diagram, the focal length of the diverging lens.
18N.3.SL.TZ0.8b.ii:
Hence state how the defect of the converging lens in (a) may be corrected.
20N.3.SL.TZ0.11c:
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.
19M.3.SL.TZ2.11ai: Construct rays, on the diagram, to locate the image of this object formed by the lens. Label...
18N.3.SL.TZ0.9b.i:
Calculate the distance between the lenses.
17M.3.SL.TZ1.7a.iii:
The distance between the lenses is 18 cm. Determine the focal length of L₂.
19M.3.SL.TZ2.11aii:
Determine, by calculation, the linear magnification produced in the above diagram.
17M.3.SL.TZ1.7a.ii:
Show that the image of the object formed by L₁ is 12 cm to the right of L₁.
17M.3.SL.TZ1.7a.iv:
On the diagram draw rays to locate the focal point of L₂. Label this point F.
17M.3.SL.TZ2.8b:
Explain your sketch in (a)(i).
16N.3.SL.TZ0.12a: Identify the nature of the lens.
16N.3.SL.TZ0.12b:
Determine the distance between the lamp and the lens.
19M.3.SL.TZ2.11aiii: Suggest an application for the lens used in this way.
19M.3.SL.TZ2.11bi: Identify, with a vertical line, the position of the focussed image. Label the position I.
17M.3.SL.TZ1.7a.i:
State what is meant by a virtual image.
18N.3.SL.TZ0.8b.i:
Suggest how the refracted rays in (a) are modified when the converging lens is replaced by a diverging lens.
17N.3.SL.TZ0.9b.i:
Determine the position of the image.
19N.3.SL.TZ0.7a(iii): Describe two features of the image.
16N.3.SL.TZ0.11b:
The incident ray shown in the diagram makes a significant angle with the optical axis.

(i) State the aberration produced by these kind of rays.

(ii) Outline how this aberration is overcome.
19N.3.SL.TZ0.7a(i):
Construct a ray diagram in order to locate the position of the image formed by the mirror. Label the image $I$ .
19N.3.SL.TZ0.7a(ii):
Estimate the linear magnification of the image.
19N.3.SL.TZ0.7b(ii):
Explain chromatic aberration, with reference to your diagram in (b)(i).
19N.3.SL.TZ0.7b(iii): An achromatic doublet reduces the effect of chromatic aberration. Describe an achromatic...
19N.3.SL.TZ0.7b(i): Sketch, on the diagram, the wavefront of red light passing through point P. Label this...
19N.3.SL.TZ0.8a: State what is meant by normal adjustment when applied to a compound microscope.
19N.3.SL.TZ0.8b:
Calculate, in cm, the distance between the eyepiece and the image formed by the objective lens.
18M.3.SL.TZ1.8a.ii:
The lens is 18 cm from the screen and the image is 0.40 times smaller than the object. Calculate the power of the lens, in cm^–1.
16N.3.SL.TZ0.12c:
Calculate the focal length of the lens.
20N.3.SL.TZ0.10a: Construct a single ray showing one path of light between the eye, the mirror and the object,...
20N.3.SL.TZ0.11a:
Draw on the diagram the three wavefronts after they have passed through the lens.
20N.3.SL.TZ0.10b: The image observed is virtual. Outline the meaning of virtual image.
20N.3.SL.TZ0.11d:
Calculate the total magnification of the object by the lens combination.
17M.3.SL.TZ2.8a.ii:
On the diagram, sketch the wavefront in air that passes through point P. Label this wavefront Y.
17M.3.SL.TZ2.8c:
Two parallel rays are incident on a system consisting of a diverging lens of focal length 4.0 cm and a converging lens of focal length 12 cm.

The rays emerge parallel from the converging lens. Determine the distance between the two lenses.
18M.3.SL.TZ1.8a.i:
Identify whether the image is real or virtual.

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Option C: Imaging » Option C: Imaging (Core topics)

Option C: Imaging