ELECTRICITY+3

Electricity is an integral part of modern life and powers many of the everyday objects around us. Most primary school children will be familiar with electricity, or that it exists, but are unlikely to understand how it works. To comprehend this it is important that children know that everything is made up of tiny atoms that cannot be seen by the naked eye and there are even smaller parts which make up these atoms, including an electron which is negatively charged. A circuit is made when the positive and negative sides of the battery are connected by wires. The battery, or cell, works because the chemical inside it creates a surplus of electrons at the negative terminal and a deficit at the positive terminal. When the terminals are connected by a wire the negative electrons are attracted to the positive terminal, which creates an electrical flow around the wire. Electricity can travel through the wires because they have a conductive material inside them (copper wire), insulated by the outer coating (plastic).
 * ELECTRICITY: by Laura, Lauren, Rebecca & Katie.**
 * What is electricity?**

A conductor is a material that allows electricity to pass through it and the easier it is for electricity to pass through the material, the better a conductor it is. An insulator is a material that does not let electricity flow through it, or lets very minimal amounts pass through it. For a material to conduct electricity, it must have electrons that are free to move between atoms. Examples of conductors: metal, water, people (!) Examples of insulators: plastics, wood, rubber
 * Conductors and Insulators**


 * Current:**
 * Electrical current is the flow of charge around a circuit. The battery acts as a pump driving the electrical current around the circuit, in a similar way that a pump drives water.
 * The current can only flow if the circuit is complete.
 * The electrical current is a flow of NEGATIVE electrons around a circuit.
 * Current is measured in amps: an ammeter measures how much charge is flowing through the circuit.
 * Current is the same everywhere in a series circuit (see below for definition).
 * Current is NOT used up by components in a circuit.
 * The current in a series circuit is dependent on the number of cells (batteries). If you add more cells to the circuit the current will increase.

There are two types of electric circuit - series and parallel.
 * Circuits**:

Series: A series circuit only has one path for the electrons to flow through.

Parallel: A parallel circuit has more than one path for electrons to flow through. If one bulb breaks the other will still be lit because there is still a path for the electrons.

Circuit Diagrams: We can draw circuit diagrams using the following symbols:

Misconceptions: One of the most common misconceptions is that batteries contain electricity, acting as a 'source' of electricity for the circuit. The battery actually contains chemicals which give the electricity already in the wires a 'push' or 'pull' to to move it round the circuit.

__**The history of electricity:**__

In 1858 electric cables were spliced together in the middle of the Atlantic Ocean in order to join Newfoundland electronically with Ireland. A cable message was sent using morse code from Queen Victoria to the American President James Buchanan. Unfortunately, the message was very slow, so Wildman Whitehouse tried to speed up the process by increasing the voltage. This increase in voltage increased the pressure and the cable stopped working.

In 1866 a clear cable message was sent from Ireland to Newfoundland. This transformed the world as it took only seconds now to send messages.

In the 1860's gas was used to light homes. The problem with this was that gas lamps were too dull to light the outside effectively. Sir Humphrey Daley invented electric arc lights which created a continuous spark of electricity across carbon rods. Unfortunately these lights produced a very bright white light which was too bright to be suitable for use within the home.

In the early 1880's Thomas Eddison sought to develop a different type of lamp. With the help of a large team of engineers Eddison tested different types of filament. He tested platinum which was very effective as it did not melt, however it was too expensive. He even tested the beard hair of one of engineers.

In 1882, Eddison ambitiously sought to light New York. Through his knowledge of electrical engineering, Eddison had built up a reputation which meant that he had the financial backing behind his ambitious plans. In 1882, he lit up the first power station with his incandecsant light bulbs at a cost of half a million dollars. Eddison recognized the dangers of electricity so insisted upn the cables being buried underneath the ground. At this time, the streets would have resembled a messy maize with cables running above the ground. Eddison argued that cables buried under the ground would reduce the risk of electrocution and fires, however, burying all the cables was quite expensive. Unfortunately, the range of the power station was only 1 mile so it was not economical to run.

Nikola Tesla sought to use different types of electrical current, he developed an alternative current in which the current would move in one direction and then in the opposite direction. This concept was different to Bell's direct current in which the current only moved in one direction.

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