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प्रश्न
Suppose you have focused on a screen the image of candle flame placed at the farthest end of the laboratory table using a convex lens. If your teacher suggests you to focus the parallel rays of the sun, reaching your laboratory table, on the same screen, what you are expected to do is to move the:
(a) lens slightly towards the screen
(b) lens slightly away from the screen
(c) lens slightly towards the sun
(d) lens and screen both towards the sun
उत्तर
(a) lens slightly towards the screen
To focus the parallel rays of the Sun, the lens should be slightly moved towards the screen.
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संबंधित प्रश्न
Define focal length of a divergent lens.
An image formed by a concave ______ cannot be obtained on a screen.
A concave lens always forms a virtual image.
A real image cannot be obtained on a screen.
State two differences between a convex and a concave lens.
Explain why, a stick half immersed in water appears to be bent at the surface. Draw a labelled diagram to illustrate your answer.
Write the new Cartesian sign convention for spherical lenses.
If a spherical lens has a power of, −0.25 D, the focal length of this lens will be :
(a) −4 cm
(b) −400 mm
(c) −4 m
(d) −40 cm
A convex lens forms an image of an object equal to the size of the object. Where is the object placed in front of the lens?
Complete the following table for convex lens:
| Sr. No. | Position of the object | Position of the image | Nature of the image |
| 1. | Beyond 2F1 | __________________ | ________________________ |
| 2. | __________________ | At infinity | ________________________ |
| 3. | __________________ | __________________ | Real, inverted and enlarged |
