A student is performing an experiment to study the formation of image of a lighted candle by a converging lens. The converging lens has a focal length of 25 cm and the candle is placed at a distance of 15 cm from the lens.
(a) State three characteristics of the image of the candle so formed which will be observed by the student.
(b) Name a simple device which works under these conditions.

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Solution

(a) The focal length of the given lens is 25 cm. The object is placed at 15 cm, that means the object lies between the pole and the focus of the lens. The characteristic of the image formed by the convex lens, in this case, are as follows:

(1) The image formed would be erect
(2)The image formed would be virtual.
(3) The image formed would be enlarged

(b) A convex lens is used in a magnifying glass and in simple microscope where we need to see the object enlarged than its normal sizes such as while reading a book or a magazine.

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