Question

Find the equivalent resistance between the points $A$ and $B$.

• A. $3\Omega$
• B. $4\Omega$
• C. $5\Omega$
• D. $6\Omega$

Answer 1

The correct option is D $6\Omega$

We can redraw the circuit as -


All the resistors between points $A$ and $1$ are in parallel.

Their equivalent resistance can be calculated as,

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

$\therefore R_{eq}=1\Omega$

Between points $1$ and $2$, both the resistors are in parallel.

$\frac{1}{R_{eq}}=\frac{1}{4}+\frac{1}{4}=\frac{2}{4}=\frac{1}{2}$

$\therefore R_{eq}=2\Omega$


Hence,

$R_{AB}=1+2+3=6\Omega$