A system consists of a convex lens and a concave mirror placed at a distance of x from the lens. Focal length f1 of convex lens in 10 cm and focal length f2 of mirror is 60 cm. If an object is placed at a distance 20 cm from the lens and it is found that the final image coincides with the object position, then what must be the distance 'x'
Answers
Since the object is placed 20 cm from the lens it is at a distance 2 f from the lens.
The image formed will be at a distance 2f" role="presentation" style="display: inline; font-style: normal; font-weight: normal; line-height: normal; font-size: 13px; text-indent: 0px; text-align: left; text-transform: none; letter-spacing: normal; word-spacing: normal; word-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px; margin: 0px; position: relative;">2f2f ie 20 cm from the lens at 0 '.
So if the concave mirror is placed at this position , the 1st image will be at the pole of the mirror so it will reflect symmetrically and the final image will be at 0 itself.
Therefore x=20cm