Electrical symbols Plug problems Earthing Circuit breakers Electrical

Electrical symbols Plug problems Earthing Circuit breakers Electrical safety a. c. theory

You should know all these by name and what they do! previous next smart

Adding these in series will decrease the current previous next smart

It’s graph curves as it gets hotter previous next smart

This one is open previous next smart

You choose the one above the current That should be flowing normally previous next smart

V Connect in parallel to measure the pd previous next smart

Provides a pd previous next smart

Low resistance when connected the right way round but no current will flow when it is the wrong way round previous next smart

Increasing light levels makes this have a lower resistance previous next smart

Increasing the temperature makes this devices resistance go down previous next smart

Changing its value increases and decreases the current previous next smart

A Connected in series to measure the current previous next smart

More than 1 cell is called a ____ previous next smart

This one is closed previous next smart

1 fixed resistor 2 lamp 3 open switch 4 fuse 5 voltmeter 6 cell 7 diode 8 LDR 9 thermistor 10 variable resistor 11 ammeter 12 battery 13 closed switch

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Plugs are a simple and safe way of connecting things to a mains circuit. In Britain the squarepin fused plug is the most commonly used type. When wiring a plug, check that: • The wires are connected to the correct terminals: Brown to Live Blue to Neutral Yellow and green to Earth • There are no loose strands of wire • The cable is held firmly by the grip • A fuse of the correct value is fitted previous next smart

What is wrong with these plugs? previous next smart

E L N previous next smart

E N L previous next smart

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When you plug in an electrical device, you are connecting it into a circuit. The circuit hasn’t got a battery in it. But the mains Supplying electricity which Keeps changing direction. We call this an alternating current

Insulated cable Live fuse 230 V a. c. Neutral Earth previous next smart

The ____ wire has a brown covering The ____ wire is a safety wire The ____ wire goes alternately + and – The ____ wire has a blue covering The ____ covering wire has a green and yellow

Higher level The live terminal of the mains supply between a positive and negative voltage with respect to the terminal. The neutral terminal stays at a voltage close to with respect to earth. previous next smart

answers live earth live neutral earth Higher level Alternates Neutral zero

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The neutral wire is kept at zero potential. The live wire potential alternates (changes) from positive to negative. This causes an alternating potential difference (p. d. ) current 0 volts p. d. (volt) previous +338 -338 0 volts next smart

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fuse Earth A fault, such as the live wire touching the metal case can be dangerous. Earthing the case provides a low resistance path so a large current flows to earth, melts the fuse, breaks the circuit and stops the current. previous next smart

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Large of current Normalsurge current Push down to reset after the fault has been corrected Iron rocker This coil of wire wrapped round a piece of iron is an electromagnet which gets strong enough to attract the rocker when there is a surge of current previous next smart