JEE Main · 2021 · 31 Aug 2021 · Shift 2 · Current Electricity

The equivalent resistance of the given circuit between the terminals

A

and

B

is :

Answer: (B)

Solution

The left-edge wire short-circuits the

5 Ω

resistor, so it carries no current and is removed, leaving its top node at the potential of

B

. The two

3 Ω

resistors meeting at

A

are in parallel,

\frac{3 \times 3}{3 + 3} = 1.5 Ω

. At the next node the vertical

2 Ω

and the horizontal

2 Ω

returning to

B

are in parallel,

1 Ω

, which adds in series with the

2 Ω

joining that node to

A

to give

3 Ω

. This

3 Ω

path is in parallel with the

1.5 Ω

A

R_{A B} = \frac{3 \times 1.5}{3 + 1.5} = 1 Ω.

JEE Main · 2021 · 31 Aug 2021 · Shift 2 · Single correct option