Question

why does voltage decreases in series circuit and no any change in parallel circuit?

Answer 1

Because Current.

Consider a circuit to be starting from +ve side of the battery and ending on the -ve end. The current on each such circuits are constant.

Thus the series is a continuous circuit but the parallel can be assumed as 3 seperate circuits.

If V be the voltage then in parallel R1,R2,R3 are having V voltage. While in series R1+R2+R3 is having V voltage. So in each resistance the voltage gets divided


Hope this helps u...