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(copy) Grade 10 Electricity

by Nicholas Govender

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St Peter's College

Grade 10 Electricity
Introduction

Static electricity is very useful and is used for example when making photocopies. However, most electrical devices need an electric current. Washing machines, TVs, heaters and stoves are a few examples of devices, which are used in almost all households. We can hardly imagine a life without electricity. Just think about the inconvenience a power failure can cause!

The electrical current was discovered by accident! In the early 1700s, Luigi Galvani succeeded in moving the legs of a dead frog with a charge. However, one day it happened without a charge. Alessandra Volta came to the conclusion that a chemical reaction between the copper hooks, from which the frog was suspended, and the iron of the stand, has caused an electric current. He made the first battery after thus observation. Batteries are commonly used as source of electricity and are commonly used in flashlights.
You can learn more about the history of electricity from this video: (not examinable)
In a South African context, most of our electricity is provided by ESKOM and is generated in power stations. Most of the electricity used in South Africa is generated in a coal power station. The burning coal heats water and the formed steam drives a turbine which in turn drives a generator (Figure 1). The electricity is then transported over long distances to sub-stations, from which it is spread to households. We will investigate electric current in this unit and focus on the movement of charges in a circuit and the measurement of other quantities which influence current.
In a South African context, most of our electricity is provided by ESKOM and is generated in power stations. Most of the electricity used in South Africa is generated in a coal power station. The burning coal heats water and the formed steam drives a turbine which in turn drives a generator (Figure 1). The electricity is then transported over long distances to sub-stations, from which it is spread to households. We will investigate electric current in this unit and focus on the movement of charges in a circuit and the measurement of other quantities which influence current.
In order for an electric current to flow you need an electric circuit. A simple circuit will contains a minimum of three types of components:
1) an energy source
2) conducting material
3) a component that converts electrical energy into another form of usable energy e.g. a lightbulb converts electrical energy into heat and light

An example of a complete circuit consisting of a battery, light bulb and connecting wires is shown in the picture below.
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