CBSE 2025 · Region 6 · Set 1 · Q17 · 2 marks
Find the equivalent resistance between points A and B for the network shown in the figure.

Marking-scheme solution
Resistance between points C and B
\[\begin{aligned}
& \frac{1}{\mathrm{R}}=\frac{1}{\mathrm{R}_{1}}+\frac{1}{\mathrm{R}_{2}}+\frac{1}{\mathrm{R}_{3}} \\
& \frac{1}{\mathrm{R}}=\frac{1}{15}+\frac{1}{45}+\frac{1}{45} \\
& \mathrm{R}=9 \Omega \\
& \text { Equivalent resistance between points } \mathrm{A} \text { and } \mathrm{B}
\end{aligned}
\]
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