Question

What is the effective resistance between the points A and B in the network shown in figure?

• A. $1.0\Omega$
• B. $1.5\Omega$
• C. $4.5\Omega$
• D. $2.5\Omega$

Answer 1

The correct option is A $1.0\Omega$

In this case, the 2 resistors of 1 ohm and 2 ohms on the upper half of the circuit are connected in series and the combined resistance R1 is given as 1+2 = 3 ohms.
The resistances R1 and 1.5 ohms in the middle are connected in parallel. So the total resistance R of this parallel connection is given as $\frac{1}{3}+\frac{1}{1.5}=\frac{1}{1}=1ohm$. That is, the resistance in the closed loop is reduced to 1 ohm.
Hence, the value of the resistance in the circuit between A and B is 1 ohms.