Every electrical appliance in your home — from the kettle to the air conditioner — carries a small label printed with numbers and letters: V, A, and W. These three letters are the key to understanding everything that follows in this series: how to choose the right wire, how to read your bill, and why a breaker trips.
Voltage — The Driving Force
Voltage, measured in volts (V), is the "driving force" that pushes electrons to move through a wire. In most countries, the home network supplies sockets with 220-240 volts between phase and neutral (some countries, like the United States, use 120 volts). This voltage stays roughly constant regardless of which appliance is connected — it's a property of the grid, not the device.
Current — The Amount of Flow
Current, measured in amperes (A), is the amount of electrons flowing through a wire each second. Unlike voltage, current depends on the connected appliance: a small fan draws less than one amp, while an electric heater might draw 10 amps or more from the very same socket at the same voltage.
Power — The Rate of Energy Consumption
Power, measured in watts (W) or kilowatts (kW = 1000 watts), is the rate of energy consumption, calculated by multiplying voltage by current:
| Appliance | Approximate Voltage | Approximate Current | Power |
|---|---|---|---|
| LED bulb | 220 V | 0.045 A | ≈10 W |
| Electric kettle | 220 V | ~9 A | ≈2000 W |
| 1.5-ton split AC unit | 220 V | ~6 A | ≈1300 W |
The relationship P = V × I is the foundation of every calculation in this series: choosing the right wire size, sizing a circuit breaker, and reading your electricity bill. If you memorize this single equation, you'll understand the logic behind every article that follows.
Sample answer: Voltage (volts) is the driving force supplied by the grid and stays roughly constant (220-240 volts), current (amps) is the amount of flow and depends on the connected appliance, and power (watts) is the rate of energy consumption, calculated by multiplying voltage by current: P = V × I. The higher an appliance's power at a fixed voltage, the more current it draws from the grid.
Confusing amperes (the instantaneous rate of current flow) with kilowatt-hours (the amount of energy consumed over a period of time, which is the unit used on your electricity bill). Amperes relate to a moment of operation, while kilowatt-hours relate to time — we'll explain this difference in detail in an upcoming article.
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