Kirchhoff’s Laws

Node = point in a circuit where two or more elements meet

Current (KCL)

The algebraic sum of currents at any node is equal to zero

$$\sum _{n=1}^N{i}_n=0$$

Convention

• Going in = negative
• Going out = positive

Voltage (KVL)

• The sum of voltages around a closed path is 0
• The sum of voltage drop = sum op voltage rise

$$\sum _{n=1}^N{v}_n=0$$

Steps

• Add voltages in a clockwise fashion
• Assign a + to the voltage across the element if + terminal is encountered first
• Assign a - if the - terminal is encountered first

Applying

1. Identify known values
2. Identify unknown values
3. Define and set up KVL loop equations
4. Apply Ohm’s law
5. Apply KCL equations to find known values
6. Solve
7. Verify