Question

The ray diagram below illustrates the experimental set up for the determination of the focal length of a converging lens using a plane mirror.

1. State the magnification of the image formed.
2. Write two characteristics of the image formed.
3. What name is given to the distance between the object and the optical centre in the diagram above?

The ray diagram alongside illustrates the experimental set up for the determination of focal length of a converging lens using a plane mirror.

1. State the magnification of the image.
2. Write the characteristics of the image formed.
3. What name is given to the distance between object and optical centre of lens.

Answer 1

(a) The magnification is

m = −1

The negative sign indicates that the image is inverted.

(b) The image is real, inverted and the same size as the object.

(c) The object is placed at the principal focus of the convex lens. Therefore, the distance between the object and the optical centre of the lens is the focal length of the lens.