Q. Out of five resistances of resistance $R\ \Omega$ each 3 are connected in parallel and are joined to the rest 2 in series. Find the resultant resistance
A) $\left( \frac{3}{7} \right)R\ \Omega$
B) $\left( \frac{7}{3} \right)R\ \Omega$
C) $\left( \frac{7}{8} \right)R\ \Omega$
D) $\left( \frac{8}{7} \right)R\ \Omega$
Explanation
(b) $\frac{1}{R_{P}} = \frac{1}{R} + \frac{1}{R} + \frac{1}{R} = \frac{3}{R}$
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$\Rightarrow R_{P} = \frac{R}{3}\Omega$
$\Rightarrow R_{S} = R + R = 2\ R\Omega$
$\Rightarrow R_{net} = R_{P} + R_{S} = 2R + \frac{R}{3} = \frac{7R}{3}\Omega$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.