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Chp 18 Electricity

Chp 18 Electricity. What is Electricity?. A form of energy Used to make electrical appliances work. Electric Current. It is the rate of flow of electrical charge. The path that the current flows through is known as a circuit. Electric Current. Drawing circuit diagrams. Battery Switch

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Chp 18 Electricity

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  1. Chp 18 Electricity

  2. What is Electricity? • A form of energy • Used to make electrical appliances work

  3. Electric Current • It is the rate of flow of electrical charge. • The path that the current flows through is known as a circuit.

  4. Electric Current

  5. Drawing circuit diagrams • Battery • Switch • Light bulb • Resistor • Variable resistor/rheostat • Voltmeter • Ammeter

  6. Potential Difference: • The potential difference across any two points is the amount of energy needed to move one unit charge of electricity from one point to the other.

  7. Resistance • Resistance of the object = Potential difference across its ends Current flowing through it

  8. Effects of an Electric Current Electrical energy can be transformed into other forms of energy to produce many effects

  9. Heating Effect of a Current • Wire heats up as a current passes through it • Electrical energy is converted into heat energy • Heat produced depends on the resistance of the wire • Greater resistance, greater heat

  10. Heating Effect of a Current • Heating appliances have coils of wires made of high resistance materials such as nichrome • Heating elements heat up when current passes through them • Heat produced is then used for ironing, toasting, cooking and drying

  11. Heating Elements in Heating Appliance

  12. Heating Appliances

  13. Magnetic Effect of a Current • An iron rod placed inside a coil of wire has increased magnetic field when the current is switched on • When the current is switched off, the iron loses its magnetism • The set-up is known as an electromagnet

  14. Magnetic Effect of a Current • Used in many applications • Gives a magnetic field that can be switched on and off when desired

  15. Applications of the Magnetic Effect of Current • Giant electromagnet • Telephone • Electric motors

  16. Chemical Effect of a Current • Liquids such as salt water, vinegar and copper sulphate solution allow electricity to pass through them • Liquids are known as electrolytes

  17. Chemical Effect of a Current • Electrolysis: Chemical decomposition of an electrolyte by an electrical current • Electrodes: Two wires or plates through which current enters and leaves the electrolyte

  18. Application of the Chemical Effect of Current • Electrolysis is used in electroplating • Flow of current causes a thin layer of metal to be deposited on the object to be electroplated • Electrolysis is also used in industries to extract metals such as aluminium and magnesium from their compounds

  19. Applications of Electroplating

  20. Lighting Effect of a Current • Heating effect of a current can also lead to the lighting effect • In a light bulb, the heat generated is so great that the coiled filament begins to glow and give out light

  21. Miscellaneous • http://www.pge.com/microsite/PGE_dgz/wires/resist.html • http://www.bgfl.org/bgfl/custom/resources_ftp/client_ftp/ks2/science/electricity_book1/index.htm

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