Ohm's Law and Kirchhoff's Laws

Ohm's Law and Kirchhoff's Laws

All electronics analysis starts with three equations. Master these and you can analyze any circuit.

Ohm's Law

V = I · R

• V = voltage (Volts) — electrical pressure
• I = current (Amperes) — charge flow rate
• R = resistance (Ohms) — opposition to flow

Kirchhoff's Current Law (KCL)

The sum of currents entering a node equals the sum of currents leaving it.

ΣI_in = ΣI_out

No charge accumulates at a junction.

Kirchhoff's Voltage Law (KVL)

The sum of voltage drops around any closed loop equals zero.

ΣV = 0  (around any loop)

Power

P = V · I = I² · R = V² / R

Power dissipated as heat in a resistor — critical for thermal management of motor drivers.

Practical Note

When you size a motor driver for CatBot, you need to know:

1. Peak current draw (from motor datasheet)
2. Supply voltage
3. Continuous vs. peak thermal load

These three quantities come directly from Ohm's Law and power calculations.