A convex lens has a focal length of 10 cm. Find the location and nature of the image if a point object is placed on the principal axis at a distance of (a) 9.8 cm, (b) 10.2 cm from the lens.

Answer

A, B, C, D

Explanation

a. `f=10 cm, u=9.8`
1/v-1/u=1/f`
`1/v=1/f+1/u=1/10-1/9.8`
`1/v=(9.8-10)/98=(-0.2)/98`
`v=-98xx5` ltbgt `=-490cm`
(same side of object)
`v=490cm`
on the side of object (virtual)
b. u=10.2
`1/v=1/10-1/10.2`
`=(10.2-10)/102=0.2/102`
`v=102xx5=510cm(real)`
(opposite side of object)