Question

A concave mirror forms a real image of a point source lying on the optical axis at a distance of $50\text{cm}$ from the mirror. The focal length of the mirror is $25\text{cm}$. The mirror is cut into two equal parts and each of the two halves are rotated about $S$ by ${90}^{\circ }$, one in anticlockwise and other in clockwise with reference to the original position, then the distance between the two images formed by each part will be

• A. $3\text{cm}$
• B. $2\text{cm}$
• C. $1\text{cm}$
• D. $0\text{cm}$

Answer 1

The correct option is D $0\text{cm}$

According to the given situation,


From the diagram, we can see that the object will lie at the centre of curvature of both the parts. Thus, the images will also form at the centre of curvature. Hence, the images coincides and distance between them is zero.