# What is the method to calculate the minimum no. of resistors to be connected in a circuit to get a certain resistance in a closed loop? [closed]

Ex : What is the minimum number of 2 Ohm resistors which has to be connected to have an effective resistance of 1.5 Ohms?

• @pentane : So far I have no idea to solve this question and that's why I posted this message – Aathesh Vigram May 1 '18 at 15:51

$1.$ The total resistance you want to obtain is greater than you already have in your circuit.
In this case you have to add a resistance in series. Seeing how for two resistances connected in series you have : $$R_{tot} = R_{1} +R_{2}$$ you have need to solve a very simple equation and obviously you only need one resistance.
$2.$The total resistance you want is smaller than what you have.
In this case you have to add a resistance n parallel. However this time : $$\frac{1}{R_{tot}} = \frac{1}{R_{1}} + \frac{1}{R_{2}}$$ Again simple equation and you only need one resistance.