An object of size 7.5 cm is placed in front of a convex mirror of radius of curvature 25 cm at a distance of 40 cm. The size of the image should be

Options

A. 2.3 cm
B. 1.78 cm
C. 1 cm
D. 0.8 cm

Answer

B

Explanation

Magnification,
`m=(l)/(O)=(f)/(f-u)`
`therefore " " (l)/(7.5)=((R//2))/((R//2)-u)=((25//2))/((25//2)-(-40))`
`therefore " "` The size of the image, `l=-1.78 cm`