13 - Conduction - Multiple Resistances

\[Q = \frac{T_A-T_B}{R_{\text{total}}}\]

\[\begin{aligned} R_{\text{total}} &= R_{\text{(1 and 2)}} + R_3 \\ &= \frac{1}{\dfrac{1}{R_1}+\dfrac{1}{R_2}} + R_3 \\ &= \frac{R_1R_2}{R_1+R_2} + R_3 \end{aligned}\]