Q 12-03-150JEE MainJEE Main 2023 (10 Apr, Shift 1)Medium
The equivalent resistance of the circuit shown below between points $a$ and $b$ is
Answer: (B) $3.2\ \Omega$
The four $4\ \Omega$ resistors around the top and centre points form a balanced Wheatstone bridge (top and centre are at the same potential), so the top–centre $4\ \Omega$ carries no current.
Paths $a$–top–$b$ and $a$–centre–$b$ are each $8\ \Omega$: together $4\ \Omega$. In parallel with $16\ \Omega$:
$$R=\frac{4\times16}{20}=3.2\ \Omega$$
Solution by Sreeraj P, M.Sc Physics