## College Physics (4th Edition)

$A = 1.50\times 10^{-4}~mm^2$
First we can express the area in units of $m^2$. Note that $1 ~\mu m^2 = 1\times 10^{-12}~m^2$ $A = 150~\mu m^2\times \frac{1\times 10^{-12}~m^2}{1~\mu m^2}$ $A = 150\times 10^{-12}~m^2$ We can express the area in units of $mm^2$. Note that $1 ~mm^2 = 1\times 10^{-6}~m^2$ $A = (150\times 10^{-12}~m^2) \times \frac{1~mm^2}{10^{-6}~m^2}$ $A= 150\times 10^{-6}~mm^2$ $A = 1.50\times 10^{-4}~mm^2$