What is the purpose of a resistor in a circuit?
September 21, 2011 10:36PM
A resistor limits the amount of electrical current that passes through the circuit.
Think of kinking a garden hose. The kink "resists" the flow of water.
Similarly, a resistor "resists" the current flow and thus lowers the voltage to the following parts of the circuit which that current has to flow through.
Simple...To resist or control the current flow.
If a pure conductor (ie, wire) instead of a resistor is used, the path is said to be short circuited and, in theory - but not usually in practice - an infinite current would flow through it if the source was really able to deliver such a current.
But, if there is some resistance in its path, the current taken from the source will always be limited to the potential difference produced by the source (measured in volts) divided by the resistance of the path (measured in ohms).
I = E/R (Where I is current, E is volts and R is resistance)
Another use of a resistor is whenever you need to produce a voltage drop in a circuit. This drop can can then be utilized for some other purpose, noting the voltage will differ depending on the load. If the load varies in resistance, so will the voltage drop.
When no resistors are met by the current, the voltage which is actually the amount of work done in moving the charge will tend to zero. This means that the current flows without any resistance and is said to be a dead short to the source.