You are supplied with a number of 100 Ω resistors. How could you combine some of these resistors to make a 250 Ω resistor?
To make equivalent resistance of 250 ohms one may connect:
1) 2 resistors in series Thus, the resultant would be:
100+100= 200 ohms
2) 2 resistors in parallel Thus, the resultant of 2 parallel combination would be:
3) Now connect the combination of the two (series and parallel) in series: Thus, we may obtain a net resistance of: 200+50 = 250 ohms