Calculate the equivalent resistance between A and B in the following circuits :

To evaluate the resistance between two points A and B which are called given points, we will do the questions by imagining that a battery is attached to these two points A and B and there is formation of complete circuit, so these two points would have potential difference(V) and hence resistors attached to these two points by both sides would be parallel to each other because of same potential difference across the ends.

Therefore we can’t merge these two points, we can’t merge the other points just by looking at them blindly.

We will solve the questions by diagram wise and not by writing for proper understanding.

The diagram above is our question figure, Now the 2 ohm resistors other than the triangle base resistor or not including the triangle base resistor, the other two resistors are in series and hence we can add them simply to get a new resistor,

2ohm + 2ohm = 4 ohm,

Due to the change in potential difference of the top point these two resistors are in series. As we know if the potential difference is same then the resistors are parallel.

Hence our figure is resolved, which is,

Now the 4 ohm resistor and the 2 ohm resistor are in parallel as we have discussed before about the two given points which are

A and B.

So,

R = 4/3 ohm,

Hence our answer is 4/3 ohm and the answer is always when there is only one resistor remaining.