Answer to Question #344163 in Optics for benson

Question

A pencil that is 10.0 cm long is held perpendicular to the surface of a plane mirror with the tip of the pencil lead 12.0 cm from the mirror surface and the end of the eraser 21.0 cm from the mirror surface what is the length of the end of the image of the pencil that is formed by the mirror which end of the image is closer to the mirror surface: the tip of the lead or the end of the eraser?

Answer 1

In object point of view tip of the lead is closer to the surface of the plane mirror with a distance of 12 cm, Therefore, in image point of view tip of the lead is closer to the surface of the plane mirror with a distance of -12 cm.