Amps, Volts, and Watts
Understanding Electrical Units
Learn Electrical UnitsAmps, volts, and watts describe different aspects of electricity. Understanding their relationship helps you choose the right charger, size electrical circuits, and understand your electric bill.
The Three Units
Volts (V) - Electrical Pressure
- Force that pushes electrons through a circuit
- Higher voltage = more "push"
- US household: 120V; Europe: 230V
Amps (A) - Electrical Flow
- Amount of charge flowing per second
- Higher amps = more electrons moving
- Household circuits: 15-20A
Watts (W) - Electrical Power
- Rate of energy use
- Watts = Volts × Amps
- 60W bulb uses 60 joules per second
Key Formulas
- P = V × I (Power = Voltage × Current)
- V = I × R (Voltage = Current × Resistance)
- P = I² × R (Power = Current² × Resistance)
- P = V² / R (Power = Voltage² / Resistance)
Practical Examples
| Device | Voltage | Current | Power |
|---|---|---|---|
| Phone charger | 5V | 2A | 10W |
| LED bulb | 120V | 0.08A | 10W |
| Microwave | 120V | 8.3A | 1000W |
| Space heater | 120V | 12.5A | 1500W |
Conclusion
Volts measure electrical pressure, amps measure flow, and watts measure power. The fundamental relationship P = V × I connects them all. Understanding these units helps with everything from charging devices efficiently to sizing home electrical circuits safely.