Question

Fourteen identical resistors each of resistance $R$ are connected as shown in the figure. The equivalent resistance between the points $A$ and $B$ is

• A. R
• B. 14 R
• C. $\frac{R}{14}$
• D. 1.2 R

Answer 1

Answer: (D)

With respect to points $A$ and $B$, the points $C$ and $D$ are equipotential points. $E$ and $F$ are equipotential points. The circuit is redrawn as


$\frac{1}{R^{\prime }}=\frac{2}{R}+\frac{2\times 3}{2R}=\frac{5}{R}$ or $R^{\prime }=\frac{R}{5}$
Hence, the equivalent resistance between $A$ and $B$ is
$R_{AB}=R^{\prime }+R=\frac{R}{5}+R=1.2R$