Question

You are supplied with a number of $100\Omega$ resistors. How could you combine some of these resistors to make a $250\Omega$ resistor?

Answer 1

To make the equivalent resistance of 250 $\Omega$ one may connect:

1) 2 resistors in series

Thus, the resultant would be: 100+100= 200 $\Omega$

2) 2 resistors in parallel

Thus, the resultant would be: $\frac{100\times 100}{100+100}=50\Omega$

3) Now, connect the combination of the two (series and parallel) in series:

Thus, we may obtain a net resistance of 200+50 = 250 $\Omega$