A beam of light converges towards a point `O` ,behind a convex mirror of focal length `20` cm.Find the nature and position of image if the point `O` is-
(1) `10`cm behind the mirror, (2) `30`cm behind the mirror

Explanation

Here object is virtual
`u=10cm,f=20cm,v=?`
`(1)/(v)+(1)/(u)=(1)/(f)`
`(1)/(v)+(1)/(10)=(1)/(20)impliesv=-20cm`
O: virtual object I: real image
(b) `u=30cm,f=20cm,v=?`
`(1)/(v)+(1)/(u)=(1)/(f)`
`(1)/(v)+(1)/(30)=(1)/(20)impliesv=60cm`
O: virtual object I: virtual image