Question

an object is placed at a distance of 20 cm is in front of a plane mirror find distance between object and it's image​

Answer 1

The plane mirror being moved 2cm nearer the object predicts the image to move 2×2=4cm ahead of the original image. Other wise the initial position of image was at 2×20cm from the object. As the mirror moved 2cm towards the object its new distance from mirror becomes 18cm.Then, the new distance of image from object becomes 2×18=36cm.Hence the distance betwen the two images=(40–36)cm=4cm.