In the above question, the correct value...

In the above question, the correct value of focal length `f` of lens as calculated from the graph is :

`f = (1)/(OA)`

`f = (1)/(OA + OB)`

`f = (1)/(OA -OB)`

`f = (1)/(OB)`

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The correct Answer is:

In a convex lens, when object is at infinity, image is at focus, i.e.
when `u = oo, (1)/(u) = 0`,
`(1)/(v) = OB = (1)/(f) :. F = 1//OB`.

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An object is placed in front of a converging lens at a distance equal to twice the focal length f_(1) of the lens. On the other side of the lens is a concave mirror of focal length f_(2) separated from the lens is a concave mirror of focal length f_(2) separated from the lens by a distance 2(f_(1)+f_(2)) . Light from the object passes rightward through the lens, reflects from the mirror, passes leftward throught the lens, and forms a final image of the object.

The distance between the lens and the final image is equal to `2f_(1)`.

The distance between the lens and the final image is equal to `2(f_(1)+f_(2))`

The final image is real, inverted and of same size as that fo the object.

The final image is real, erect and of same size as that of the object.

P = f

`P = (1)/(f)`

`P = -(1)/(f)`

`P = -f`

f/2

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