When an object is at distances x and y from a lens, a real image and a virtual image is formed respectively having same magnification. The focal length of the lens isA. `(x+y)/2`B. x-yC. `sqrt(xy)`D. x+y

When an object is at distances x and y from a lens, a real image and a

1.	When an object is at distances x and y from a lens, a real image and a virtual image is formed respectively having same magnification. The focal length of the lens isA. `(x+y)/2`B. x-yC. `sqrt(xy)`D. x+y
Answer» Correct Answer - A (a) For real image, u=-x v=+mx `1/(mx)-1/(-x)=1/f` For virtual image, u=-y Then, v=-my `1/(-my)-1/(-y)=1/f` On solving Eqs. (i) and (ii) we get `f=(x+y)/2`

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When an object is at distances x and y from a lens, a real image and a virtual image is formed respectively having same magnification. The focal length of the lens isA. `(x+y)/2`B. x-yC. `sqrt(xy)`D. x+y

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