During a thunderstorm, have you seen a flash of bright light in the sky? This is called 'lightning' and is an example of electrical energy. It is the visible discharge of atmospheric electricity moving between clouds or from clouds to the ground. As lightning heats the air, it creates a shock wave that causes the sound of thunder.
In this lesson we will learn about:
Electrical energy is a type of kinetic energy caused by moving electric charges. These charged particles are called electrons. The amount of energy depends on the speed of the charges – the faster they move, the more electrical energy they carry. Let's imagine an electrical charge is represented by a ball being thrown against a window. If you throw the ball very fast, it will have more energy to break the window. If you don't throw the ball fast, it won't have enough energy to break the window.
Power lines are used to transmit and distribute electrical energy.
Electricity is a type of energy that comes from electrical energy.
Kinetic energy is the energy of a moving object.
Electric trains use electricity to power electric motors, driving their wheels and providing movement.
Some examples of electrical energy are:
Electrical energy can be potential or kinetic energy. It results from the flow of an electrical charge. Energy can be seen as the work required to move an object or subject it to a force. Let's take the example of a battery - in a battery, electrical energy is often potential energy until some force is applied to make the charged particles do some work and become kinetic energy. When you switch on your light at home, the potential energy travels down the wire and is converted into light and thermal energy.
Before electrical energy is delivered to the end-user, all electrical energy is potential energy. Once it is converted from potential energy, we can always call electrical energy as another form of energy like light, heat, motion, etc.
Now, let's look at two other important terms in relation to electrical energy - electric charge, electric field, and electric current.
An electric charge is a basic property of matter carried by some subatomic particles (e.g. electrons and protons) that govern how these particles are affected by an electromagnetic field. Electric charge can be positive or negative, occurs in discrete units, and is neither created nor destroyed. It causes attractive and repulsive forces between the particles. Like-charged objects repel and opposite-charged objects attract one another. Coulomb's law determines the magnitude of the force of attraction or repulsion.
An electric field is the physical field that surrounds electrically charged particles and exerts a force on all other charged particles in the field, either attracting or repelling them.
An electric current is a flow of electric charge in a circuit. It is the rate of charge flow past a given point in an electric circuit. The electric current is measured in coulombs per second, and the commonly used unit is Ampere (amp, A).
The following illustration shows negatively charged particles moving through a wire in an electric circuit creates electricity
Electrical energy is generated when mechanical energy is harnessed and used to rotate a turbine. The mechanical energy to spin the turbine can come from a variety of sources, including falling water, wind or steam from heat generated either by a nuclear reaction or by burning fossil fuels.
For example:
In a nuclear power plant, nuclear energy heats water into steam The steam is used to turn a turbine blade, which fires up a generator to give electric charges their energy.
In a hydroelectric plant, falling water is used to spin the turbine blades. The blades turn the generator to create electrical energy.
Solar energy is energy produced directly from the sun. Solar energy can be converted into electricity or used to heat air, water or other fluids.
In a windmill, wind power turns the turbine blade, which – you've guessed it! – makes the generator create electrical energy.
Below is a picture of windmills:
The basic unit of electrical energy is the Joule.
The commercial unit of electrical energy is the kilowatt-hour (kWh).
Electrical energy can be converted into other forms of energy like heat energy, light energy, motion, etc. The best-known examples are:
Can you think of any other example of the transformation of electrical energy into other forms of energy?
