WHAT IS ELECTRICITY?
It is amazing how electric charges work!
Bill Nye is crazy!! You can learn about static electricity with him.
Conductors are materials that carry electrical current easily. Copper, silver and most other metals are good conductors.
Insulators are materials that do not let electricity pass through them. Wood, plastic or rubber are examples of insulators.
In the diagram you can see the conducting wire wrapped in insulating plastic
DO YOU WANT TO PLAY?
CONDUCTORS AND INSULATORS
An electrical circuit is formed by various elements connected in a way that allows the circulation of an electrical current. Click on the image to play with them.
And if you want to make an experiment with static electricity click on the image below
DO YOU KNOW HOW ELECTRICITY IS GENERATED?
Many of the appliances that we use, both at home and outside, work thanks to electrical energy. We live in a society that is totally dependent on electricity. This is why it is essential to know how it is created and what are its main characteristics.
Electrical energy is one of the most common energies in our daily lives, as many of the appliances around us need it to work. From the electrical appliances in our homes to street lighting and even electronic devices and multimedia equipment. Electricity is a manifestation of electrical energy.
Electricity can be created artificially in:
- Electric power stations: where it is produced from other types of energy such as hydraulic or wind energy.
- Batteries: in which it is produced from chemical energy.
Chemical energy is what is obtained from chemical reactions or changes in matter. These are processes that change the nature of a substance and transform them into another. Combustion, oxidation and fermentation are chemical reactions.
However, although electricity can be generated using these methods, it is not in itself an artificial phenomenon, as it can be found naturally in the Universe. One of the clearest displays of electricity in nature is lightning. These electrical phenomena are caused by electric charges that exist in the atmosphere. Electrical energy also exists in living organisms. For example, in the electrical signals that the nervous system sends to show that you have touched something with your hand.
Have you ever felt a spark when you touch a person or an object? This happens because your body or the object are electrically charged, that is, they have electric charges. Electric charges are particles of matter that create electrical phenomena, such as sparks and lightning.
Electric charges can be positive or negative. When a body has the same number of positive and negative charges, we can say that it is an electrically neutral body. The majority of objects that surround us are electrically neutral, that is, their positive and negative charges are balanced.
However, negative charges often easily pass from one body to another and this causes imbalances. As a result, we can distinguish between:
- Negatively charged bodies: these are bodies with more negative charges than positive ones.
- Positively charged bodies: these are bodies with more positive charges than negative ones.
The electrically charged bodies relate to one another depending on the sign of their charges:
- When the bodies have the same charge sign, they repel one another. That is, if we put two positively charged bodies together, these tend to separate from one another. The same thing happens with two negatively charged bodies. This can be seen, for example, if we rub two filled balloons with wool and then put them together. We can see how the balloons move away from one another.
- When the bodies have a different charge sign, they attract one another. That is, if we move a positively charged body to a negatively charged body, these tend to stay together. We can see this, for example, if we rub a plastic stick with wool and then hold it near little pieces of paper. In this case, we will see how the pieces of paper are attracted to the plastic.
You can learn more about electric charges and static electricity in this animation by the Consejería de Educación del Gobierno de Canarias [see].
Sometimes, when we rub specific materials together, it produces a strange effect that makes them attract or repel one another. For example, after brushing hair a lot with a plastic comb, it is possible that the plastic slightly attracts our hair. This is because it is charged with static electricity. Static electricity also causes the crackling that we can hear when we take off a woollen jumper or the spark that can sometimes occur when we touch another person or a metal object.
Electricity can move inside bodies. When this circulation happens in an orderly way, it is called electric current. This electric current is the orderly circulation of electric charges which occur through the electric cables in our homes.
3.1Conductive materials and insulating materials
We can say that electric current moves inside bodies, but not all bodies allow electric current to move inside them. Depending on a material’s ability to transmit electric current, we can distinguish between conducting and insulating materials:
- Conductive materials: are materials that allow electricity to pass through them. For example, most metals are good electrical conductors.
- Insulating materials: are materials that do not allow electricity to pass through them, such as rubber and glass.
Electric cables make it possible to transport electricity. There are made with copper, a conductive material that makes it possible for electric current to flow freely inside it. Each copper conductor is usually covered with an insulating material, such as plastic, which prevents the loss of electric current. Finally, cables made up of several conductors are covered with a common plastic covering, which is more rigid and protects them from external agents (temperature, rain, sunlight, knocks, etc.).
An electrical circuit is a group of components that have been joined together to allow electric current to flow and to be distributed. The basic elements of an electrical circuit are as follows:
- Current generator: element that provides the circuit with electric current. It can be a battery or the mains electricity.
- Conducting element: element that conducts the current through the circuit. It is usually copper cable.
- Electronic receiver or device: element that uses electric current to work. An electrical circuit may have more than one electronic receiver. These may be bulbs or electrical appliances.
- The switch: element that opens or closes the electrical circuit. When the switch allows the electric current to flow through the circuit, we say that it is a closed circuit. On the other hand, if the switch is open, the circuit is interrupted and the electric current does not flow through it.
If you would like to check if you have correctly understood how an electrical circuit works, you can do this interactivity, which has a test at the end [see].
3.3The uses of electric current
Electric current is very useful in our daily lives, as it provides electricity to a huge number of appliances that we use in our homes, at school or even in our free time. Among its main uses, we can highlight three very important ones:
- Light: Electric current allows us to have artificial light to illuminate our homes and the streets. Light bulbs generate light, and so do televisions and computers. When light is produced, electrical energy is transformed into light energy.
- Heat: electric current is also used to create heat. In this case, electrical energy is converted into thermal energy through appliances such as heaters, dryers and ovens.
- Motion: electric current can be used to create motion, using motors that transform electrical energy into mechanical energy. Trains, industrial machines, lifts and escalators all work thanks to electric current.
3.4The production and transport of electricity
Electricity can be found naturally in living organisms and in nature. But what we use in our homes and in industry is produced artificially in electric power stations.
Electric power stations transform different types of energy into electrical energy using electromagnetic generators. They are made up of a cable coil that turns between two magnets and this produces electricity. This mechanism , in turn, is driven by a turbine, which consists of a giant wheel or helix. Different types of energy can be used to move the turbine and the generator.
Depending on the type of energy they use and the source they obtain it from, we can distinguish between various types of electric power stations:
- Thermal power station: this uses thermal energy or the heat created from burning fossil fuels to heat water and produce steam that moves the generator.
- Nuclear power station: this uses the heat or thermal energy that is obtained from the fusion of atoms of matter to heat water and create steam that moves the generator.
- Hydroelectric power station: this uses the mechanical energy of water from rivers to make the generator rotate.
- Tidal power station: this uses the mechanical energy of the tides to make the turbines turn, which moves the generator.
- Wind power station: this uses the mechanical energy of the wind to move the generator.
- Solar photovoltaic power station: this type of power station does not use generators to produce electricity. Photovoltaic panels transform light energy from the Sun into electrical energy without any need for generators.
- Solar thermal power station: this uses the thermal energy that the Sun releases to produce steam that makes the turbines, and in turn, the generator rotate.
- Geothermal power station: this uses the thermal energy of the Earth to heat water and create the steam that makes the generator turn.
- Biomass power station: it uses the thermal energy obtained from burning waste to heat water, which produces the steam that moves the generator.
There are different types of energy:
- Mechanical energy: is created by a body in movement.
- Thermal or calorific energy: is the energy released by bodies in the form of heat.
- Light or luminous energy: is the energy that transmits light.
- Electrical energy: is the energy that moves through an electric current.
- Chemical energy: is the energy released in chemical reactions.
- Nuclear energy: is the energy contained in atoms of matter.
Electricity generated in electrical power plants must be distributed throughout an area so that all users have power, including: private homes, businesses, public places, etc. This distribution is carried out through the electric network or grid, which can be in the air or underground.
ELECTRICITY AND MAGNETISM
Have you ever used a magnet? When you put a magnet near an object made of iron or other metals, they will immediately stick to it. The property with which magnets attract metals is called magnetism. Magnetism is very closely related to electricity, as it can produce magnetism and vice versa. The relationship between electricity and magnetism is called electromagnetism.
In ancient Greece, a mineral was discovered called magnetite, which attracts certain metal objects like iron. This property was named magnetism.
Magnets are bodies that have the property of attracting metals, especially iron and steel, so we would say that they have magnetic properties. The area that surrounds the magnet is able to attract other bodies and is known as a magnetic field.
Magnets have two ends that are called poles. One of them is called the south pole or positive and the other is called the north pole or negative. In the same way as electric charges, if the poles are the same sign, they repel one another and if they are of a different sign, they attract one another.
Magnetic poles and compasses
The core of the Earth is made up of a mixture of metals, making it work like a huge magnet. The Earth has a north magnetic pole and a south magnetic pole, which are located near to the geographic poles. The discovery of this fact made it possible for the compass to be invented in the 3rd century in China. The compass is an instrument that, thanks to a magnetised needle, precisely points to the direction and polarity of the Earth’s magnetic axis. It is very useful to know your position, as it allows you to know where each geographic pole is wherever you are.
Electromagnetism is the branch of physics that studies the relationship between magnetic fields and electrical phenomena.
Electric current, when moving through an electrical circuit, creates a weak magnetic field. This magnetic field can increase its intensity if we roll the cable that the electric current moves through around a piece of iron. As the magnetic field is intensified, it creates a kind of magnet, known as an electromagnet.
Electromagnets behave in the same way as magnets. They attract certain metals, provided that an electric current moves through the circuit. At the moment that the electric current stops flowing, the piece of iron loses its magnetic properties.
Additionally, in the same way that electricity creates magnetism, magnetism can also create electricity. When you move a magnet close to an electric cable, it creates a weak electric current inside it. The stronger the magnet is and the faster it moves, the more electric current it will create. This is what the mechanism of electromagnetic generators is based on, which are devices that can produce electricity from the movement of magnets.
Electromagnetic generators are used in electrical power stations to produce electricity. Electromagnetic generators are basically made of a coil of copper cable that turns between two magnets. This movement transforms different types of energy into mechanical energy, which is what makes the coil turn.