A convex lens of focal length f produces a real image m times the size of an object, then the distance of the object from the lens is

Options

A. (m + 1)f
B. (m - 1)f
C. `((m+1)/m)f`
D. `((m-1)/m)f`

Answer

C

Explanation

We have,
magnification = `f/(f+u)=-m`(given)
or f = -mf - mu
or mu = -(m + 1)f
`thereforeu=-((m+1))/mf`
So, distance of the object from the lens is `((m+1)/m)f`.