Question

Seven resistors, each of value 5 $\Omega$ are connected as shown in figure. The equivalent resistance between points A and B is:

• A. $5\Omega$
• B. $7\Omega$
• C. $14\Omega$
• D. $35\Omega$

Answer 1

The correct option is B $7\Omega$

Equivalent circuit of the above figure is shown which represents a special type of unbalanced wheat stone bridge.

If $\frac{P}{Q}=\frac{S}{R}=n$,

then equivalent resistance between A and B

$R_{eq}=\frac{3n+1}{n+3}r$

From figure, $n=2$

$⟹$ $R_{eq}=\frac{3\left(2\right)+1}{2+3}\times 5=\frac{7}{5}\times 5=7\Omega$