8 ELECTRICITY AND MAGNETISM

 8. Electricity and magnetism

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Caption: : THOMAS EDISON

 ELECTRICAL CHARGES

 When we rub a pen against a wool jumper and then  hold the  pen near some small pieces of paper, the pieces will stand up  and stick to the pen.  This happens because of electrical charges. The pen becomes electrically charged whe it is rubbed against something. Then, it is able to attract small objects. All objects aroun us, such as your body or the stars, have electrical charges.

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Caption: : Electrically charged plastic pen

Types of electrical charges

 Electrical charges  can be positive or negative. Obejects around us usually have the same number of positive and negative charges. This means they are electrically neutral.  However, negative charges can move from one  object to another. When non-metal objects are rubed againts  each other , they gain or lose negative charges and become electrically charged. An object that gains negative charges becomes  negatively charged .  An object that loses negative charges becomes positively charged. 

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Caption: : exchange of electrical charges

Interaction between electrical charges

 Electrically charged objects interact with each other in two different ways: Objects with the same charge repel. They push away from each other. Objects with opposite charges attract. They pull towards each other.

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 ELECTRIC  CURRENT

An electric current is the flow of electrical charges through materials. When more electrical charges circulate , the electric current is stronger and more electricity flows. Electricity carried in an electric current can easily be transformed into other forms of energy.

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Conductors and insulators

Materials can be clasified into two types, depending on how easily electrical charges can flow through them. Conductors. This are materials that allow electrical charges to move freely. Insulators . This are materials that do not allow electrical charges to move.

The effect of electrical curres

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Caption: : ( : PHILIPS : )

HEAT LIGHT  SOUND MAGNETISM MOVEMENT  CHEMICAL EFFECTS

ELECTRIC CIRCUITS

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Caption: : Circuits diagrams

An electric circuit is a closed path through which eletricity flows.  The circuit needs to form a complete circle in other to work. We use circuit diagrams to illustrate circuits.  

Components of electric circuits

The generator. This provides the electricity. Cables. This transport the electricity from the generator to the other components of the circuit. Devices. This transform the electricity into another type of energy. The switch. This controls the flow of electricity by closing or opening the circuit. 

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Caption: : Electric circuit

Production of electricity

Most electrical appliances do not work with batteries. They must be connected to the electrical grid through a socket. Every socked is conected by cables  to a national grid,which supplies electriciti created in power plants. 

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Caption: : electrical grid

Power plant

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Caption: : Power plants

 Power plants produce electricity from different  energy sources. In thermal power plants, fosil fuels , uranium or plutonium are used to heat up water. In wind power plants,wind moves a turbine  wich is connected  to a generator. In hydroelectric power plants, water moves  a turbine which is connected to a generator. In solar power plants, heat or light from the Sun are used to produce electricity. Solar panel absorbs light from the sun, which is converted directly into electricity.

Magnetism

                                    MAGNETS A magnet is an object wich attracts other objects made  of  iron and other  magnetic metals.  We call this atraction magnetism. Magnets can be natural or artificial.  Some minerals, like magnetite, attrct metallic objects .

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Caption: : magneto

Magnetic forces

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All magnets have two areas, called poles. These areas are known as the  north magnetic pole (N) and the south magnetic pole (S). Magnetic forces can act at a distance. When we put two magnets next to each other, they can attract or they can repel each other.

Caption: : MAGNETIC FORCES

The Earth's magnetism

However, the  magnetic  poles of the Earth are opposite to the geographic poles. The North Magnetic Pole is found in the South, near the South Pole, and the  South Magnetic  Pole is found in the north, near the North Pole.

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