Watt/hour (Wh) and kWh

Watt

The watt (symbol: W) is the unit of measurement of the Power of the International System and is equivalent to 1 Joule per second: 1 J / s or it is the instantaneous power produced or consumed.

Note: Joule is the obstacle that faces the current when it passes through a conductor

In electrical units, it is equivalent to 1 volt multiplied by ampere: W = V * A, which in electrical engineering is equal to the electrical power (P) that passes through a section of the circuit and is given by the product of voltage (V) and current (I) present in the section considered:

P = V × I (Unit of measurement of power is Watt, abbreviated: W)

Some of the most used multiples and submultiples:

• Milliwatt (mW) = 10-³ w = 0.001 w
• Kilowatts (kW) = 10³ w = 1000 w
• Megawatt (Mw) = 10⁶ w = 1,000,000 w
• Gigawatt (Gw) = 10⁹w = 1,000,000,000 w
• Terawatt (Tw) = 10¹² w = 1,000,000,000,000 w

Watt/Hour

The Watt-hour (Wh) is the unit of measurement derived from energy, defined as the total energy supplied if a power of one watt (W) is maintained for one hour (h).

The Watt-hour is not part of the international system that provides for the Joule for measuring Energy, and only some of its multiples are used, such as the kilowatt-hour (kWh), which is typically used in the sale of electricity.

Since 1W = 1J /s and 1h = 3600s, then it results: 1Watt * h = 1 (W) * 3600 (Sec) = 3600 * J / Sec = 3600J = 3.6 kJ

For example, an apparatus with a power of 1000 Watt (W) that remains on for 1 hour will "consume" 1000 Wh = 1 kWh of Energy corresponding to 3.6 MJ (3600 kJ)

In the sale of Energy, its multiples such as kilowatt-hour, megawatt-hour, gigawatt hour and terawatt hour are used. The milliwatt hour (mWh) is sometimes used to indicate the energy content of stylus batteries.