Which are the five sources of electrical energy?

• A. Magnetism, chemical energy, light, heat, and pressure
• B. Gravity, velocity, inertia, sound, and color
• C. Fire, ice, wind, water, earth
• D. Heat, pressure, mass, time

Answer: (A)

Electrical energy can be produced by converting different energy forms: magnetic energy, chemical energy, light energy, thermal energy, and mechanical pressure. Generators rely on magnetism to induce current as a conductor moves within a magnetic field. Batteries store chemical energy that becomes electrical energy when discharged. Light energy can be turned into electricity with photovoltaic cells that generate current from photons. Heat energy can be converted to electricity through devices like thermoelectric generators or by using heat to drive a turbine that powers a generator. Mechanical pressure or stress can be transformed into electricity via piezoelectric materials or other pressure-based energy harvesters.

The other options mix forms that aren’t direct sources of electrical energy in typical devices, such as gravity or color, or group energy forms in nonstandard ways.