Question

A point object is placed in the middle of two concave mirrors. The focal length of each mirror is 10 cm to obtain single image of point object, the distance between two mirrors in cm will be

• A. 10
• B. 20
• C. 30
• D. 40

Answer 1

The correct option is D 40

To form a single image of point object the first image should be formed at such a place that its consecutive image coincide with it so that even after multiple reflection all the image should over lap and form a single image.
there is only one point where image and object lie at same place that is center of curvature.
so the point object should be placed at center of curvature of both mirrors that means $2\times f=2\times 10=20cm$ from each mirror. The distance between mirrors will be $20+20=40cm$.