[问答题]
A double-glazed window has two pan
6+kgjiwy 2x 6wl(r6(jz wl7ybes of gl
nf fnslml g 1*.6v,u)eass separated by an air space, Fig. 14–20. (a) Show that the rate of heat flow through suc
. fmn) 6ngevls1 luf,*h a window by conduction is given by
$\frac{Q}{t}$ = $\frac{A(T_2-T_1)}{l_2/k_1+l_2/k_2+l_3/k_3}$,
where $k_1$,$k_2$ and $k_3$ are the thermal conductivities for glass, air, and glass, respectively. (b) Generalize this expression for any number of materials placed next to one another.
