Question

what is the equivalent resistance in this series??​

Answer 1

Answer: 2 ohms

Explanation:

As you can see in the image below, let us name the four junctions first, based on their potentials. If the first junction is 'A', then the third junction also must be 'A' because there is no potential drop from the first to third junction (see the wire connecting them).

But, from the first to second junction there is a resistor, causing a potential drop. Let us name this 'B'. The fourth junction, again, must be the same potential as 'B', because from the second to fourth junction there is a wire with no potential drop.

Hence, we see that all the three resistors are in parallel — connected to the same potential drops. In other words, all three are connected from 'A' to 'B'. The potential difference across all three resistors is the same. Therefore we consider them to be in parallel.

Then we use the equation for resistors in parallel.

1/R1 + 1/R2 + 1/R3 = 1/R

Where R is the net resistance. On solving the equation by substituting R1 = R2 = R3 = 6 ohms, we arrive at R = 2 ohms.

Thank you! I hope it helped.