Question

An object is placed in front of a convex mirror at a distance of 50 cm. A plane mirror is introduced covering the lower half of the convex mirror. If the distance between the object and the plane mirror is 30 cm, it is found that there is no gap between the images formed by the two mirrors. The radius of the convex mirror is:

• A. 12. 5 cm
• B. 25 cm
• C. 50 cm
• D. 100 cm

Answer 1

The correct option is B 25 cm


$\frac{1}{f}=\frac{1}{v}+\frac{1}{u}\frac{1}{f}=\frac{1}{10}+\frac{1}{-50}=\frac{-5+1}{-50}=\frac{-4}{-50}=\frac{2}{25}f=\frac{25}{2}\Rightarrow R=25cm$
So, option (B)