5262611
Description
Flashcards by Anisha Rai, updated more than 1 year ago
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Created by Anisha Rai
over 8 years ago
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| Question | Answer |
| What do cells and batteries supply? | Current that always passes in the same direction (Direct Current) |
| What is an alternating current? | A current that is constantly changing direction |
| Is this the oscilloscope reading of an a.c or d.c? | Direct current |
| Is this the oscilloscope reading of an a.c or d.c? | Alternating current |
| Which supply is mains electricity? | Alternating current |
| What is the frequency of mains electricity in the UK? | 50 cycles per second (50 hertz) |
| What is the potential difference of the mains electricity in the UK? | About 230V |
| What may a diode be used for? | Half wave rectification of a.c |
| How are most electrical appliances connected to the mains? | Using a cable and a three-pin plug |
| What colour is the live wire? | Brown |
| What colour is the neutral wire? | Blue |
| What colour is the earth wire? | Green and yellow stripes |
| What happens if an electrical fault causes too great a current flow? | The circuit is disconnected by a fuse or a circuit breaker in the live wire |
| What happens when the current in a fuse wire exceeds the rating of the fuse? | It will melt, breaking the circuit |
| What is the link between cable thickness and fuse value? | The thicker the wire in the fuse, the higher the fuse's rating |
| What are RCCBs? | Residual Current Circuit Breakers They protect circuits Operate much faster than a fuse |
| How do RCCBs operate? | By detecting a difference in the current between the live and neutral wires |
| What usually happens to appliances with metal cases? | They are usually earthed |
| Do appliances that are double insulated have an earth wire connection? | No |
| What do the earth wire and fuse do? | Protect the wiring of a circuit |
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