Practice question

**Simple microscope** magnification M = 1 + D/f when image at D=25 cm near point, M = D/f when image at infinity (relaxed eye), f focal length (cm), D least distance of distinct vision 25 cm. For f=4 cm, image at 25 cm, M=1+25/4=7.25, angular magnification ratio of angle subtended by image to that by object at D. The maximum magnification of a single lens (simple microscope) is limited by its focal length. A shorter focal length increases magnification (m = 1 + D/f), but practical constraints like lens aberrations and the minimum focal length achievable restrict it to around 9-10x, necessitating a compound system.