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प्रश्न
Explain the rules for obtaining images formed by a convex lens with the help of ray diagram.
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उत्तर
- Rule 1: When a ray of light strikes the convex or concave lens obliquely at its optical centre, it continues to follow its path without any deviation.
Rays passing through the optical centre - Rule-2: When rays parallel to the principal axis strikes a convex or concave lens, the refracted rays are converged to (convex lens) or appear to diverge from (concave lens) the principal focus
Rays passing parallel to the optic axis - Rule-3: When a ray passing through (convex lens) or directed towards (concave lens) the principal focus strikes a convex or concave lens, the refracted ray will be parallel to the principal axis
Rays passing through or directed towards the principal focus
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संबंधित प्रश्न
A lens forms an erect, magnified, and virtual image of an object. Draw a labelled ray diagram to show the image formation.
Draw a ray diagram to show how a converging lens can form a real and enlarged image of an object.
Draw a ray diagram to show how a converging lens can form an image of the sun. Hence give a reason for the term ‘burning glass’ for a converging lens used in this manner.
Where should an object be placed so that a real and inverted image of the same size is obtained by a convex lens?
A small bulb is placed at the principal focus of a convex lens. When the bulb is switched on, the lens will produce
An object is placed at a distance 20cm from a convex lens of focal length 10cm. Find the image distance and nature of the image.
Draw ray diagrams showing the image formation by a convex lens when an object is placed
- between optical centre and focus of the lens
- between focus and twice the focal length of the lens
- at twice the focal length of the lens
- at infinity
- at the focus of the lens
A student focussed the image of a candle flame on a white screen using a convex lens. He noted down the position of the candle screen and the lens as under
Position of candle = 12.0 cm
Position of convex lens = 50.0 cm
Position of the screen = 88.0 cm
- What is the focal length of the convex lens?
- Where will the image be formed if he shifts the candle towards the lens at a position of 31.0 cm?
- What will be the nature of the image formed if he further shifts the candle towards the lens?
- Draw a ray diagram to show the formation of the image in case (iii) as said above.
Complete the following table based on image formation by convex lens:
| Position of Object | Position of Image | Nature of Image |
| At infinity | (a) ______ | Real and inverted and highly diminished image |
| Beyond 2F1 | (b) ______ | (c) ______ |
| At 2F1 | (d) ______ | Real, inverted, same size (as object) image |
| Between F1 and 2F1 | Beyond 2F2 | (e) ______ |
| At focus F1 | (f) ______ | Real, inverted and highly enlarged image |
A lens forms an upright and magnified image of an object. Draw a labelled ray diagram to show the image formation.
