Theory:

Image formation in a convex lens
1. A convex lens is fixed on a stand for support and placed on the table.
2. A cardboard sheet of \({15\ cm} \times{10\ cm}\) is taken, and a white sheet is pasted on it. This sheet will act as a screen.
3. A candle is lighted and placed at a certain distance from the convex lens.
4. The candle is placed on the other side of the lens, and its position is adjusted to obtain a sharp image of the flame on the screen.
5. Even the screen is also adjusted to get the image of the flame.
 
Inference
When the lens is placed at a large distance from the object, the image formed is real, inverted and smaller (or highly diminished) than the object.
 
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When the lens is moved a little closer to the object, the image formed will be real, inverted and magnified on the screen.
 
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If the convex lens is brought even closer to the object, the image will not be formed on the screen. But, it can be viewed on the mirror as a virtual, erect and highly magnified image.
 
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Use of convex lenses
1. Convex lenses are used as magnifying glasses.
 
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2. Convex lenses are used in cameras to focus and magnify the image.
 
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3. It is also used in telescopes and binoculars to see distant objects clearly.
 
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Binocular and telescope
 
4. In spectacles and contact lenses, they correct vision and helps to see the objects clearly.
 
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Spectacles and a girl wearing a contact lens