What is the magnification of the image?

Question

Suppose that you have a converging lens that produces a real image of a small object. The image is at a distance of 150 cm to the left of the lens and the object is at a distance of 75 cm to the right of the lens. Please kindly show your work, thank you!

Answer 1

when the object distance is greater than the focal length of the lens, the image on the opposite side of the lens is real and inverted. The magnification is the ratio of the image height to the object height which is also given by the ratio of the image distance to the object distance.

M = H_image / H_object = - D_image / D_object = -75 cm / 150 cm = -0.5. The image height is 1/2 the object height and is is inverted as indicated by the negative sign.