/ˈɛnərdʒi/
noun … “Capacity to do work.”
Energy is a fundamental physical quantity that represents the ability of a system to perform work, produce heat, or cause physical change. In electrical systems, energy is the total work done by electric charges moving through a potential difference over time, typically measured in joules (J). Energy can exist in multiple forms, including kinetic, potential, thermal, chemical, and electrical.
Key characteristics of Energy include:
- Unit: measured in joules (J), where 1 J = 1 watt-second.
- Electrical energy: E = P × t, the product of power and time.
- Conservation: energy cannot be created or destroyed, only transformed between forms.
- Transfer: energy moves through circuits, mechanical systems, or waves.
- Storage: energy can be stored in batteries, capacitors, flywheels, or fuel for later use.
Applications of Energy include powering devices, moving machinery, heating and cooling systems, chemical reactions, and transportation.
Workflow example: Calculating energy consumption of a device:
power = 60 -- watts
time = 2 -- hours
energy = power * time * 3600 -- convert hours to seconds
print(energy) -- 432,000 J
Here, a 60 W device running for 2 hours consumes 432,000 joules of electrical energy.
Conceptually, Energy is like the fuel in a tank: it stores potential to do work and can be released in controlled ways to power systems or devices.
See Power, Voltage, Current, Electricity, Battery.