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Two lenses A and B have focal length of ...

Two lenses A and B have focal length of `+20` cm and, `-10` cm, respectively.
a) What is the nature of lens A and lens B?
b) What is the power of lens A and lens B?
What is the power of combination if lenses A and B are held close together?

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a) Lens A is convex, Lens B is concave b) Power of lens A`=+5 D`, Power of lens B`=-10 D` c) `-5D`
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LAKHMIR SINGH & MANJIT KAUR-REFRACTION OF LIGHT-Exercise
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  2. Fill in the following blanks with suitable words: a) The reciprocal ...

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  3. An object of height 4 cm is placed at a distance of 15 cm in front of ...

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  4. An object of height 4.25 mm is placed at a distance 10 cm from a conve...

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  5. A convex lens of power 5 D and a concave lens of power 7.5 D are place...

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  6. A convex lens of focal length 25 cm and a concave lens of focal length...

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  7. The power of a combination of two lenses X and Y is 5 D. If the focal ...

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  8. Two lenses A and B have focal length of +20 cm and, -10 cm, respective...

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  9. a) What do you understand by the power of a lens? Name one factor on w...

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  10. a) Two lenses A and B have power of i) +2D and ii) -4 D respectively. ...

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  11. The focal lengths of four convex lens P,Q, R and S are 20cm, 15 cm, 5 ...

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  12. A converging lens has a focal length of 50cm. The power of this lens i...

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  13. A diverging lens has a focal length of 0.10m. The power of this lens w...

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  14. The power of a lens is +2.0D. Its focal length should be:

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  15. If a spherical lens has a power of, -0.25 D, the focal length of this ...

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  16. The power of a concave lens is 10 D and that of a convex lens is 6 D. ...

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  17. The power of a converging lens is 4.5 D and that of a diverging lens i...

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  18. A convex lens of focal length 10 cm is placed in contact with a concav...

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  19. The optical prescription for a pair of spectacles is: Right eye: -3....

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  20. A person got his eyes tested by an option. The prescription for the sp...

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