Question

Example 5. A concave mirror of focal length 10 cm is
placed at a distance of 35 cm from a wall. How far from the
wall should an object be placed to get its image on the wall ?​

Answer 1

Here, f =-10cm; v =-35 cm (since the image is formed on the wall and distance between the wall and mirror is 35cm). Image is beyond 2f so object has to be in between F and C. Let the distance of the object from the wall be x. Therefore, the distance of the object from the wall = 21 cm.