Question

In the circuit shown in fig., all wires have equal resistance R ($=5\Omega$). The equivalent resistance between A and B:

• A. 10/7 $\Omega$
• B. 15/4 $\Omega$
• C. 7 $\Omega$
• D. 3 $\Omega$

Answer 1

Answer: (D)

3 $\Omega$

Simplified circuit is shown as below..
By wheatstone condition, the circuit is reduced to as shown
[ED and FC can be removed]
$\frac{1}{R_{eq}}=\frac{1}{15}+\frac{1}{15}+\frac{1}{5}$
or, $\frac{1}{R_{eq}}=\frac{2}{15}+\frac{1}{5}=\frac{5}{15}=\frac{1}{3}$
or, $R_{eq}=3\Omega$