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A point source of light is placed on the...

A point source of light is placed on the principal axis between F and 2F of a concave lens. On the other very far , a screen is placed perpendicular to principal axis. As the screen is brought close towards lens

A

(a)the light intensity on screen continuously decreases

B

(b)the light intensity on screen continuously increases

C

(c)the light intensity on screen first increases, then decreases

D

(d)the light intensity on screen first decreases, then increases

Text Solution

Verified by Experts

The correct Answer is:
B
Concave lens behaves as divergent lens and diverges the beam of light as passes from lens . When the screen is brought close towards lens it receive more number of rays hence light intensity increases.
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ALLEN -GEOMETRICAL OPTICS-EXERCISE- 01
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  2. A concave spherical surface of radius of curvature 10 cm separates two...

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  3. A double convex lens, lens made of a material of refractive index mu(1...

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  4. Optic axis of a thin equiconvex lens is the x-axis. The co-rodinates o...

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  5. A converging lens of focal length 20 cm and diameter 5 cm is cut along...

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  6. Look at the ray diagram shown ,what will be th focal length of th e1^(...

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  7. A diverging lens of focal length 10cm is placed 10cm in front of a pla...

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  8. A point object O moves from the principal axis of a converging lens in...

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  9. A point object O is placed at a distance of 20 cm from a convex lens o...

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  10. A point source of light is placed on the principal axis between F and ...

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  11. A man washign to get a picture of a Zebra photographed a white donkey ...

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  12. A lens if placed between a source of light and a wall. It forms images...

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  13. In the displacement method , a convex lens is placed in between an obj...

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  14. A beam of light consisting of red, green and blue colours is incident ...

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  15. A ray of light is incident normally on the first refracting face of th...

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  16. A horizontal ray of light passes through a prism of index 1.50 and ape...

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  17. The curve of angle of incidence versus angle of deviaton wshown has be...

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  18. A beam of monochromatic light is incident at i= 50^(@) on one face of ...

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  19. A parallel of white light falls on a concave lens , Image of blue , re...

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  20. Which of the following quantities related to a lens does not depend on...

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