All AP Physics C: Mechanics Resources
Example Question #2 : Circuit Relationships
A cicuit with a voltage source of 40V has a resistor and a resistor in series, followed by two resistors in parallel. After the parallel branches rejoin, there is a resistor before the circuit is closed at the voltage source.
What is the current supplied by the source?
The current supplied by the source can be calculated using a derivation of Ohm's law:
Start by finding the equivalent resistance of the circuit.
Sum the first two resistors in series:
Calculate the equivalent resistance of the two resistors in parallel:
Now, all of the reistances can be viewed as being in series.
Returning to our current calulation, we can find our final answer: