Question

Find the equivalent resistance in the following circuit.

• A. $4\Omega$
• B. $15\Omega$
• C. $7.4\Omega$
• D. $10.4\Omega$

Answer 1

The correct option is C $7.4\Omega$

In the given circuit, resistances $6\Omega$ and $4\Omega$ are connected in parallel combination.
$\therefore$ their equivalent resistance $R_p$ is given by:
$\frac{1}{R_p}=\frac{1}{6\Omega }+\frac{1}{4\Omega }$
$\Rightarrow \frac{1}{R_p}=\frac{6\Omega +4\Omega }{6\Omega \times 4\Omega }=\frac{10}{24\Omega }$
$\Rightarrow R_p=2.4\Omega$
Now, this equivalant resistance is connected in series combination with $5\Omega$ resistance.
$\therefore$ the effective resistance of the circuit is:
$R_{eff}=5\Omega +2.4\Omega$ = $7.4\Omega$