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Date November 2017 Marks available 2 Reference code 17N.3.SL.TZ0.9
Level Standard level Paper Paper 3 Time zone 0 - no time zone
Command term Determine Question number 9 Adapted from N/A

Question

A magnifying glass is constructed from a thin converging lens.

A converging lens can also be used to produce an image of a distant object. The base of the object is positioned on the principal axis of the lens at a distance of 10.0 m from the centre of the lens. The lens has a focal length of 2.0 m.

The object is replaced with an L shape that is positioned 0.30 m vertically above the principal axis as shown. A screen is used to form a focused image of part of the L shape. Two points P and Q on the base of the L shape and R on its top, are indicated on the diagram. Point Q is 10.0 m away from the same lens as used in part (b).

Sketch a ray diagram to show how the magnifying glass produces an upright image.

 

[2]
a.i.

State the maximum possible distance from an object to the lens in order for the lens to produce an upright image.

[1]
a.ii.

Determine the position of the image.

 

[2]
b.i.

State three characteristics of the image.

[1]
b.ii.

On the diagram, draw two rays to locate the point Q′ on the image that corresponds to point Q on the L shape.

[2]
c.i.

Calculate the vertical distance of point Q′ from the principal axis.

[2]
c.ii.

A screen is positioned to form a focused image of point Q. State the direction, relative to Q, in which the screen needs to be moved to form a focused imaged of point R.

[1]
c.iii.

The screen is now correctly positioned to form a focused image of point R. However, the top of the L shape looks distorted. Identify and explain the reason for this distortion.

[2]
c.iv.

Markscheme

with object placed between lens and focus

two rays correctly drawn

Backwards extrapolation of refracted rays can be dashes or solid lines

Do not penalize extrapolated rays which would meet beyond the edge of page

Image need not be shown

a.i.

«just less than» the focal length or f

a.ii.

1 10 + 1 v = 1 2

v = 2.5 «m»

b.i.

real, smaller, inverted

All three required — OWTTE

b.ii.

two correct rays coming from Q

locating Q′ below the main axis AND beyond f to the right of lens AND at intercept of rays

Allow any two of the three conventional rays.

c.i.

OR

2.5 or 10 × 0.3 «m»

«–» 0.075 «m»

c.ii.

towards Q

Accept move to the left

c.iii.

spherical aberration

top of the shape «R» is far from axis so no paraxial rays

For MP2 accept rays far from the centre converge at different points

c.iv.

Examiners report

[N/A]
a.i.
[N/A]
a.ii.
[N/A]
b.i.
[N/A]
b.ii.
[N/A]
c.i.
[N/A]
c.ii.
[N/A]
c.iii.
[N/A]
c.iv.

Syllabus sections

Option C: Imaging » Option C: Imaging (Core topics) » C.1 – Introduction to imaging
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Option C: Imaging » Option C: Imaging (Core topics)
Option C: Imaging

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