A point object is placed at a distance of 10 cm and its real image is formed at a distance of 20 cm from a concave mirror. If the object is moved by 0.1 cm towards the mirror, the image will shift by about

Options

A. 0.4 cm away from the mirror
B. 0.8 cm away from the mirror
C. 0.4 cm towards the mirror
D. 0.8 cm towards the mirror

Answer

A

Explanation

From the relation,
`(1)/(v)+(1)/(u)=(1)/(f)`
We have, `(-dv)/(v^(2))-(du)/(u^(2))=0`
`therefore " " dv=(v^(2))/(u^(2))(-du)=((20)/(10))^(2) (0.1)=0.4 cm " "` (away from the mirror)