A convergent beam of light passes through a diverging lens of focal length `0.2 m` and comes to focus at a distance of `0.3 m` behind the lens. Find the position of the point at which the beam would converge in the absence of the lens.

Answer

`0.12 m`

Explanation

Here, `f = - 0.2 m, v = + 0.3 m, u = ?`
As `(1)/(v) - (1)/(u) = (1)/(f)`
`:. 1()/(u) = (1)/(v) - (1)/(f) = (1)/(0.3) + (1)/(0.2) = (0.5)/(0.06)`
`u = (0.06)/(0.5) = 0.12 m`