Currents in Series and Parallel Circuits
Why is the current in each resistor of a circuit containing resistors
connected in series remain the same? Why is the current in resistors connected in
parallel in a circuit different and voltage remain same?
Imagine yourself in a large store. There are customers coming in, and always a
certain "pressure" to get out. If the store's procedure to purchase merchandise
consists of someone checking your items, then the next person pricing the items,
followed by someone totaling the order, a clerk taking payment, and finally someone
giving you a receipt, the flow through each of the five stations (resistors) is the
same. This would be analogous to resistors in series.
A competitor has all these steps at one station. When the line gets longer, a second,
third, etc. lane (station) is opened up. Some clerks are more experienced and
efficient than others. Each clerk may well have a different flow of customers.
The "pressure" of check-out is constant, but the flow of customers (current) through
each lane (branch) may be different. This is similar to a parallel circuit. In this
case, the total current is the sum of the current in each individual lane. The press
of customers, per lane, is constant.
I hope this analogy helps you understand resistors in series and parallel.
A good conceptual physics source that is easy to read and will help you is:
Paul Hewitt "Conceptual Physics" Addison-Wesley
Thanks for using NEWTON.
---Nathan A. Unterman
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Update: June 2012