1. Resistors in Series Resistors connected at a single node
Current through each resistor is the same
ECE 201 Circuit Theory I

2. Identify the current in each Resistor Apply KCL at each node
a b c d e f g
ECE 201 Circuit Theory I

3. Redraw using a single current
ECE 201 Circuit Theory I

4. To solve for the current, write KVL
ECE 201 Circuit Theory I

5. Simplified version of the circuit
ECE 201 Circuit Theory I

6. From a “black box” point of view
These circuits are “equivalent”
Same current drawn from the source
ECE 201 Circuit Theory I

7. Summary Resistors in series have the same current
The resistors can be replaced by an “equivalent” resistance equal to the sum of the individual resistors
The “equivalent” resistance is larger than the largest of the individual resistors
ECE 201 Circuit Theory I