## College Physics (7th Edition)

a). $(2)$ one with shorter focal length b). $-280X$ and $-360X$
a). (2) one with the shorter focal length should be used as objective since more is the focal length less is the total magnification of microscope as m is inversely proportional to the focal length. since, $m_{total}=-\frac{25(cm)L}{fofe}$ b). $m_{total}=-\frac{25(cm)L}{fofe}$ For lens of focal length 0.35cm, $m_{total}=-\frac{25\times 15}{0.35\times3}=-360X$ For lens of focal length 0.45cm, $m_{total}=-\frac{25\times 15}{0.45\times 3}=-280X$