Energi

Energi is a central concept in physics and everyday life, describing the capacity to perform work or generate heat. In physics, energi is a scalar quantity that can take many forms and is conserved in isolated systems. In everyday language, energi also refers to the energy resources used to power economies, such as fuels, electricity, and renewable sources. The standard unit of energy is the joule (J); larger units include kilojoule (kJ) and kilowatt-hour (kWh). Power, the rate of energy transfer or transformation, is measured in watts (W).

There are several forms of energi: kinetic energy (energy of motion), potential energy (stored energy due to position), thermal energy (related to temperature and microscopic motion), chemical energy (stored in chemical bonds), electrical energy, radiant energy (light), and nuclear energy. Energy can be transformed from one form to another through physical processes and chemical reactions, with some transformations usually producing heat as a byproduct.

Conservation: In any closed system, total energi is conserved, though its form may change. Real-world processes are often irreversible and involve dissipation, typically as heat to the surroundings, which raises temperature.

Measurement and practical use: The energy content of fuels is characterized by energy density and calorific value. Energy efficiency—how well devices convert energy into useful work—reduces consumption. Energy systems also rely on the balance and integration of supply and demand across sectors such as transport, industry, and buildings.

Context: Energi is central to science, technology, and policy, underpinning discussions of sustainability, climate change, and economic development. Growth in renewable energi sources aims to reduce environmental impact while maintaining reliable energy services.