* The least distance of distinct vision is taken to be 25cm for a normal eye.

Assuming a is a small angle, = h/D

Now consider the person to be using a simple microscope, with the object distance, u, chosen to produce an image at distance D from the lens. If the eye is placed close to the lens, the angle subtended at the eye by the image is approximately = H/D

Therefore, in this case, the angular magnification, M is given by

Therefore, when the image distance is D, the angular magnification is equal to the linear magnification.

Rearranging the lens equation gives

In this case, M = v/u and v = D, therefore

for a simple microscope with the image at the near point of the observer.

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