How is magnification (M) of a lens calculated?

The magnification (M) of a lens is calculated by taking the ratio of the height of the image to the height of the object. This relationship is expressed mathematically as M = image height / object height.

This formula indicates how much larger or smaller the image appears compared to the actual object. If the magnification is greater than one, the image is larger than the object, and if it is less than one, the image is smaller. If the image height is negative, it also signifies that the image is inverted relative to the object.

The other options do not correctly define magnification as they pertain to different concepts in optics. For instance, the second option suggests an inverse relationship that does not represent magnification correctly. The third and fourth choices involve relationships between distances and focal lengths but do not yield the magnification directly. Therefore, the correct formulation for determining magnification remains the ratio of image height to object height.