Q.
If each of the resistances in the network in figure. $R$, the equivalent resistance between terminals $A$ and $B$ is
A) $5\ R$
B) $2\ R$
C) $4\ R$
D) $R$
Explanation
(d) The equivalent circuit of these network is as shown in figure, which is a balanced Wheatstone bridge. Therefore no current will flow in the resistance of arm $PQ$. When cell is connected to points $A$ and $B$
Therefore effective resistance of arm $APS = (R + R = 2R)$ will be in parallel to the total resistance of arm $AQS( = R + R = 2R)$
$\therefore$ Equivalent resistance$= \frac{2R \times 2R}{2R + 2R} = R\Omega$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.