Mains electricity Flashcards
approximately how much volts are in U.K mains supplies?
The U.K mains supply has roughly 230 volts
what is the symbol for mains supply?
AC
what is the symbol for battery supply?
DC
what is an oscilloscope screen?
A cathode ray oscilloscope is an advanced voltmeter. If you place it in a AC supply you get a trace on the screen that shows how the voltage of supply changes with time. The trace goes up and down in a regular pattern - some positive some negative, the vertical height of the AC line shows the input voltage at that point. If you plug it in a DC supply the trace is just a straight line , the voltage is the distance from the straight line trace to the centre line
how do you work out the frequency?
1 divided by time period
name the 9 possible hazards of electrical devices
- Long cables
- Frayed cables
- Cables in heat or water
- Water near sockets
- Shoving things into sockets
- Damaged plugs
- Too many plugs into one socket
- Lighting sockets without bulbs in
- Appliances without covers on
what is the brown wire?
The brown wire is the live wire in a mains supply and is between a high positive and negative voltage
what is the blue wire?
The blue wire is the neutral wire and is always OV. Electricity normally flows through the neutral and live wire only
what is the yellow and green wire?
The earth wire is for protecting the wiring and fore safety - it works together with a fuse to prevent fire and shocks. It carries the electricity to earth if something goes wrong
which metals are used in plugs?
Copper and brass are used as they good conductors
why are the case, cable grip and insulation made of rubber of plastic?
They are good insulators and flexible
what is a fuse?
A fuse is a safety appliance built into the electrical device which melts when the current is too much to prevent the current from starting a fire or electrocuting someone
what is a circuit breaker?
A circuit breaker is a safety device that protects a circuit when too much current is flowing, if there is a large swell in current the breaker opens a switch to prevent the flow of current
what does efficient mean?
Efficient means an appliance wastes less energy
