Question

The equivalent resistance between A and B in the circuit shown will be

• A. $\frac{5}{4}r$
• B. $\frac{6}{5}r$
• C. $\frac{7}{6}r$
• D. $\frac{8}{7}r$

Answer 1

Answer: (D)

$\frac{8}{7}r$

Answer 2

In the circuit, by means of symmetry the point C is at zero potential. So the equivalent circuit can be drawn as

$R_{eq} = \left( \frac{8r}{3}||2r \right) = \frac{8}{7}r$