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Doctor has prescribed a lens having powe...

Doctor has prescribed a lens having power `+2 D ` . What will be the focal length of the lens ? What is the type of the lens and what must be the defect of vision ?

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Data : `P=+2 D, F=?`
Focal length of the lens `f=1/P =(1)/(2 D)` `= 0.5 m`
P is positive . This shows that the lens is convex. The defect of vision is farsightedness (hypermetropia).
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NAVNEET PUBLICATION - MAHARASHTRA BOARD-LENSES-Exmaples/ Numerical problems
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  2. The focal length of a convex lens is 20 cm . If an object of height 2 ...

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  8. An object is placed at 10 cm from a convex lens of focal length 12 cm....

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  9. 10 cm high object is placed at a distance of 25 cm from a converging l...

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  10. Doctor has prescribed a lens having power +2 D . What will be the foc...

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  11. An object of height 1 cm is placed in front of a concave lens of focal...

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  12. An object kept 60 cm from a lens gives a virtual image 20 cm in front ...

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  13. what is the power of a convex lens having focal length 0.5 m ?

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  14. The power of a concave lens is -2.5 dioptres. Find it focal length. ...

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  15. Calculate the focal length of a corrective lens having power +2D.

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  16. Three lenses lenses of focal length 20 cm each are kept in contact wit...

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  17. Two convex lenses of equal focal lengths are kept in contact with each...

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  18. If the convex lens of focal length 10 cm and a concave lens of focal l...

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