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

Answer

A

Explanation

mirrorr formula
`(1)/(f)=(1)/(v)+(1)/(u)implies(1)/(f)=(1)/(-20)+(1)/((-10))impliesf=(20)/(3)cm . ` If object moves towards the mirrorr by `0.1 cm` them. `u=(10-0.1)=9.9 cm`. Hence again from mirrorr formula`(1)/(-20//3)=(1)/(v^('))=(1)/(-9.9)impliesv^(')=20.4cm` `i.e.` image shifts away from the mirrorr by `0.4 cm.`