Calculate the effective resistance between the points A and B in the network below in figure (a) and (b).

Please post each question individually.

In figure (a):

Between A and B; resistors 1 ohm and 2 ohm are in series

Therefore resistance of the path ACB = 3 ohm

Now, between A and B, resistors 3 ohm and 1.5 ohm are in parallel

Therefore, net resistance 1/R_AB = 1/3 + 1/1.5

or, 1/R_AB = (1+2)/3 = 3/3 = 1

or, R_AB = 1 ohm