Question

13 resistors each of resistance $R\,\Omega$ are connected in the circuit as shown in figure. The effective resistance between A and B is

• A. $R\,\Omega$
• B. $\frac{2}{3}R\Omega$
• C. $\frac{4}{3}R\Omega$
• D. $2\,R\Omega$

Answer 1

Answer: (B)

$\frac{2}{3}R\Omega$

Answer 2

Set of 3 resistors on corner of the square mesh gives equiValant resistance as
$\frac{2R \times R}{2R + R} = \frac{2}{3}$ R . It is a balanced Wheatstone bridge so equivalent resistance is $\frac{2}{3}R$