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.

Now this is the figure given in the question, and by doing our previous questions we can see that 2 ohm resistors in upper and left directions are in series to each other and in the same way the 2 ohm resistors in the lower and right directions are in series to each other, so by solving we get,

2ohm + 2ohm = 4 ohm,

The figure gets resolved to,

Now the two 4 ohm resistors are in parallel combination to each other because of the two given points A and B, so,

R = 2 ohm,

Which is our final figure.