Q.
A circuit consists of five identical conductors as shown in figure. The two similar conductors are added as indicated by the dotted lines. The ratio of resistances before and after addition will be
A) $7/5$
B) $3/5$
C) $5/3$
D) $6/5$
Explanation
(c) Before adding, resistance is $5\ ohms.$ After the addition, the central one is a Wheatstone’s network.
$\therefore$ Total resistance is $1 + (2\ \&\ 2\ in\ parallel) + 1 = 3\Omega$
$\therefore$ The ratio of resistances $= \frac{5}{3}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.