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Ac and dc

Ac and dc. Includes plugs and shocks. Direct current. Direct current (DC) is electric current that always flows in one direction. It is produced by cells and batteries. Solar cells produce dc-the current only travels one way round. Alternating current.

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Ac and dc

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  1. Ac and dc Includes plugs and shocks

  2. Direct current Direct current (DC) is electric current that always flows in one direction. It is produced by cellsand batteries.

  3. Solar cells produce dc-the current only travels one way round

  4. Alternating current Alternating current (AC) is electric current that is constantly changing direction. It is produced by most generators and is used in mains electricity.

  5. This is the mains-the current is changing direction 50 times every second. (The frequency of mains voltage is 50Hz)

  6. Alternating versus Direct Current Thomas Edison brought direct current to the masses. Nikola Tesla proved alternating current to be more efficient. AC is supplied to our homes and many appliances run well on AC DIRECT CURRENT Some devices use direct current so a transformer converts ac to dc often at lower voltage. ALTERNATING CURRENT click for animation

  7. Voltage always positive Voltage positive and then negative ac Voltage stays positive-so dc ac

  8. 3- pin plug

  9. The live wire carries a current that alternates between a negative and positive voltage. The earth wire is a safety wire that is needed to earth appliances with a metal case. This makes it safer to touch the appliance if it develops a fault. The neutral wire completes the circuit. It is kept at a zero voltage by the electricity company. What does each wire do?

  10. The live wire carries the alternating potential difference from the supply The neutral wire completes the circuit. The earth wire is a safety wire to stop the appliance becoming live The potential difference between the live wire and the earth (0V) is about 230V The neutral wire is at or close to earth potential (0V) The earth wire is at 0V and only carries a current if there is a fault

  11. Mains Electricity USA Spain France South Africa

  12. Inside a plug The three pins in an electrical plug are connected to the three wires inside a cable. live terminal earth terminal fuse neutral terminal cable grip Could you wire a plug? cable

  13. Materials inside a plug

  14. What’s wrong?

  15. When do you get an electric shock? If you touch a live wire, there will be a potential difference between you and the ground and so a current will flow through you to the ground.

  16. How on earth…?

  17. When working normally, the current flows from the live wire, through the heating element to the neutral wire to complete the circuit. If there is a fault, the live wire may touch the metal casing and the casing becomes live. If there is no earth wire and you touch the metal casing you will get a shock. The earth wire provides an alternative low resistance pathway to the ground The current increases and blows the fuse. The earth wire protects you and the fuse protects the appliance

  18. You need to put a RCCB into the plug when using electrical garden tools

  19. Double insulated Another way of improving the safety of electrical appliances is to make them double-insulated. Double-insulatedappliances have plastic cases, without any wires connected to the case. The case cannot become live, because plastic does not conduct electricity. In the UK, double-insulated appliances are marked with a symbol of two squares.

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