Question

An object placed 4 cm in front of a converging lens produces a real image 12 cm from the lens.; (a) What is the magnification of the image?; (b) What is the focal length of the lens?; (c) Draw a ray diagram to show the formation of; Image. Mark clearly F and 2F in the diagram.

Answer 1

Answer:

-3 is the magnification and 3 is the focal length.

Explanation:

Since we know that the image is a real image and we also know from the question that the value of v = 12cm and the value of u = -4 cm.

So, the magnification is given by image distance by object distance or M=v/u which on putting the values we will get that M = 12/-4 = -3 cm.

Again, the focal length is given by the formulae 1/f = 1/v - 1/u or 1/f = 1/12 - 1/-4 which on solving we will get the value of focal length f to be  3cm.