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A candle placed 25 cm from a lens forms ...

A candle placed 25 cm from a lens forms and image on a screen placed 75 cm on the other side of the lens. The focal length and type of the lens should be

A

`+ 18.75 cm and convex lens`

B

`- 18.75 cm and concave lens`

C

`+ 20.25 cm and convex lens`

D

`- 20.25 cm and concave lens`

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TARGET PUBLICATION-OPTICS-EXERCISE
  1. An equiconvex lens has power P. It is cut into two symmetrical halves ...

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  2. A plano-convex lens of unknown material and unknown focal length is gi...

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  3. A candle placed 25 cm from a lens forms and image on a screen placed 7...

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  4. Calculate the focal length of a reading glass of a person if his dista...

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  5. A converging beam of rays is incident on a diverging lens. Having pass...

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  6. An object is located 4 m from the first of two thin converging lenses ...

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  7. A person can see clearly objects only when they lie between 50 cm and ...

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  8. Two convex lenses of focal lengths f(1)andf(2) form images with magnif...

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  9. The equiconvex lens has focal length f. If is cut perpendicular to the...

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  10. A plano-convex lens is made of material having refractive index 1.5. T...

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  11. A convex lens (with material of refractive index of 3/2) has two surfa...

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  12. A double convex lens has focal length 25 cm. The radius of curvature o...

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  13. The power of a biconvex lens is 10 dioptre and the radius of curvature...

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  14. A convex lens of glass (mu=1.5) has a focal length of 8 cm when placed...

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  15. A convex lens of glass (mu(g)=1.45) has focal length f(g) is air. The ...

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  16. A thin convex lens made from crown glass (mu=(3)/(2)) has focal f. Whe...

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  17. Two similar thin equiconvex lenses, of focal length f each, are kept c...

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  18. Two identical thin plano-convex glass lenses (refractive index 1.5) ea...

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  19. A plnao=convex lens fits exactly into a plano-concave lens. Their plan...

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  20. A plano-convex lens fits exactly into plano-concave lens as shown in t...

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