One of the two persons of same height is standing inside a shop and the other person beside a glass window outside the shop. The second man observes his magnified image due to reflection in the glass of the window. What is the nature of the glass of the window?

To a person standing at the middle point of the horizontal straight line joining the feet of two vertical posts of the same height, the angle of elevation of the top of each post appears to be 30^@ . After walking 40metres towards one of them , the person observes that the angle of elevation of the top of the same post has changed to 60^@ . Find the distance between the two posts.

A thin glass plate is placed in between a convex mirror of focal length 20cm and a point source. The distance between the glass plate and the mirror is 5cm. The image formed by the reflected rays from the front face of the glass plate and that due to the reflected rays by the convex mirror coincide at the same point. What is the distance of the glass plate from the source? Draw the ray diagram.