Problem 13.101

จาก \(V = \frac{kQ}{R}\)

\(Q =\frac{VR}{k}\)

\(\therefore Q_{1} =\frac{(10 V)(2.0 cm)}{k}=\frac{0.20}{k}C\)

\(Q_{2} =\frac{(25 V)(4.0 cm)}{k}=\frac{1.0}{k}C\)

\(Q_{3} =\frac{(30 V)(6.0 cm)}{k}=\frac{1.8}{k}C\)

จาก \(ΣQ_{f}= \Sigma Q_{i}\)

\(\frac{VR_{1}}{k}+\frac{VR_{2}}{k}+\frac{VR_{3}}{k}=\frac{0.20}{k}+\frac{1.0}{k}+\frac{1.8}{k}C\)

\(V(R_{1} + R_{2} + R_{3}) = 3.0 V\cdot m\)

\(V(2.0 + 4.0 + 6.0 cm) = 3.0 V\cdot m\)

\(V =\frac{3.0 V\cdot m}{12.0 cm}\)

\(V = 25 V \;\blacksquare\)