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The diagram given below shows the position of an object OA in relation to a converging lens whose foci are at F1 and F2.

Describe how the distance of the image from the lens and the size of the image change as the object is moved towards F1.
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A ray of light incident parallel to the principal axis of a lens, passes undeviated after refraction.
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A ray of light incident at the optical centre of lens, passes undeviated after refraction.
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For an object placed at a distance 20 cm in front of a convex lens, the image is at a distance 20 cm behind the lens. The focal length of the convex lens is ______.
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State the condition of the following:
A lens has both its focal lengths equal.
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State the condition of the following:
A ray passes undeviated through the lens.
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Fig shows an object PQ placed on the principle axis of a lens L. The two foci of the kens are F1 and f2. The image formed by the lens is erect, Virtual and dimnished.

(i) Draw the outline ofthe lens L used and Named it.
(ii) Draw a ray of light starting from Q and passing through O. show the same ray after refraction by the lens.
(iii) Draw another ray from Q Which is incident parallel to the principle axis and show how it emerges after refraction from the lens.
(iv) Locate the final image formed.
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Refer to fig
(i) Name the lens L.
(ii) What are the points O, O' called?
(iii) Complete the diagram to form the image of the object AB.
(iv) Write three characteristics of the image.

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If a monochromatic beam of light undergoes minimum deviation through an equiangular prism, how does the beam pass through the prism, with respect to its base?
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If white light is used in same way what change is expected in the emergent beam?
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Complete the ray diagram given below to show the nature of light produced on the screen.
The completed ray diagram is as shown below:

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(a) Draw a sketch to show how a lens is able to produce an image of the sun on a paper screen.
(b)(i) Would you regard the rays from the sun as being divergent, parallel or convergent?
(ii) What is the name given to the point where such rays meet after they have passed through the lens?
(iii) How does the image of the sun sometimes burn a paper screen?
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What type of lenses are used in spectacles worn by an old lady for knitting?
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