Question

An object is placed at along distance in front of a convex mirror of radius of curvature 40 cm.how far is the image behind the mirror?

Answer 1

You can find the image distance by using mirror formula,
1/f = 1/v + 1/u
Where u=Object distance (You have not given in the question)
f=R/2=40/2 =20 cm
and v=image distance