Lesson 3.4 ELECTRICAL ENERGY & POWER Form 5 KSSM

Electrical Energy is the ability of an electrical circuit to produce work by creating an action. This action can take many forms, such as thermal, electromagnetic, mechanical, electrical, etc. Electrical energy can be both created from batteries, generators, dynamos, and photovoltaics, etc. or stored for future use using fuel cells, batteries, capacitors or magnetic fields, etc. Thus electrical energy can be either created or stored. We remember from our school science classes that the “The Law of the Conservation of Energy” states that energy cannot be created or destroyed, only converted. But for energy to do any useful work it must be converted from one form into something else. For example, a motor converts electrical energy into mechanical or kinetic (rotational) energy, while a generator converts kinetic energy back into electrical energy to power a circuit. That is electrical machines convert or change energy from one form to another by doing work. Another example is a lamp, light bulb or LED (light emitting diode) which convert electrical energy into light energy and heat (thermal) energy. Then electrical energy is very versatile as it can be easily converted into many other different forms of energy. For electrical energy to move electrons and produce a flow of current around a circuit, work must be done, that is the electrons must move by some distance through a wire or conductor. The work done is stored in the flow of electrons as energy. Thus “Work” is the name we give to the process of energy. We can therefore say that Work and Energy are effectively the same as energy can be defined as “the ability to do some work”. Note that work done or energy transferred applies equally to a mechanical system or thermal system as it does to an electrical system. This is because because mechanical, thermal and electrical energies are interchangeable.