Q 12-03-192JEE MainJEE Main 2021 (31 Aug, Shift 2)Medium
The equivalent resistance of the given circuit between the terminals $A$ and $B$ is:
Answer: (D) $1\ \Omega$
Work from the left end. The plain wire at the far left shorts the $5\ \Omega$ resistor, so the left end of the first $2\ \Omega$ is connected to the bottom line.
That $2\ \Omega$ is then in parallel with the vertical $2\ \Omega$: $1\ \Omega$.
Adding the next series $2\ \Omega$: $3\ \Omega$.
The two $3\ \Omega$ resistors across $AB$ give $1.5\ \Omega$. Finally:
$$R_{AB} = \frac{3\times1.5}{3 + 1.5} = 1\ \Omega$$
Solution by Sreeraj P, M.Sc Physics