Answer (1)
Sol. Current in $\mathrm{APB}=\frac{2}{50} \mathrm{~A}$
Current in $A Q B=\frac{2}{50} A$
$\Delta V$ from $A$ to $P$
$
\mathrm{V}_{\mathrm{A}}-\frac{2}{50} \times 20=\mathrm{V}_{\mathrm{P}}
$

$\Delta V$ from A to $Q$
$
\begin{array}{l}
V_{A}-\frac{2}{50} \times 30=V_{Q} \\
V_{P}+\frac{2}{50} \times 20=V_{Q}+\frac{2}{50} \times 30 \Rightarrow V_{P}-V_{Q}=0.4 V
\end{array}
$