Question

What is the effective resistance between the points $P$ and $Q$ in the circuit shown below?

• A. $3.5\Omega$
• B. $2.5\Omega$
• C. $1.5\Omega$
• D. $4.5\Omega$

Answer 1

The correct option is C $1.5\Omega$

After rearranging the given circuit, we get,

We know for parallel combination of resistors,
$\frac{1}{R}=\frac{1}{R_1}+\frac{1}{R_2}+\frac{1}{R_3}$

Here,
$R_1=3\Omega +3\Omega =6\Omega$
$R_2=3\Omega$
$R_3=3\Omega +3\Omega =6\Omega$

$\therefore \frac{1}{R}=\frac{1}{6}+\frac{1}{3}+\frac{1}{6}$
$\Rightarrow R=\frac{3}{2}=1.5\Omega$