Physics Additional - Electricity Flashcards
What does alternating current mean?
It means the current is constantly changing direction
What is the mains voltage in the uk?
230 volts
What is the frequency of the AC mains supply?
50Hz
What do cells and batteries always supply?
Direct current
What does the oscilloscope do?
Shows the electricity supply
DC- straight line
What are the hazards in the home?
Long cables Frayed cables Cables in contact with something hot or wet Water near sockets Appliances without there covers on Shoving things into sockets Damaged plugs Too many plugs in one socket Lighting sockets without bulbs in
What colour is the live wire and what does it do?
Brown, alternates between positive and negative voltage
Electricity flows out through these wires
What colour is the neutral wire and what does it do?
Blue, electricity flows in and out
What colour is the earth wire and what does it do?
Yellow and green, it protects the wire and prevents people getting electrocuted
It works with the fuse to prevent fire and shocks and it carries electricity to earth
How does fusing and earthing work?
A fault develops and the live wire touches the metal casing
The case is earthed because too great a current flows through the live wire through the case and out the earth wire
This surge melts the fuse or trips the circuit breaker which cuts of the live supply and breaks the circuit
This isolates the appliance making it impossible to get an electrical shock from the case it also prevents fire and protects the wires from getting fried
The larger the current….
The thicker the cable needed to carry it
When does a socket plug not need a earth wire?
When it is double insulated, this is when it has a plastic case and no metal parts are showing
What should a three pin plug have?
The right coloured wire connected to each pin and firmly screwed in
No bare wires inside the plug
Cable grip tightly fastened over the cable outer layer
Different appliances need different amounts of electrical energy so thicker cables have less resistance and can carry more current
What are the plug features?
Metal parts are made of copper or brass because these are very good conductors
The case insulation is made of rubber or plastic and are good insulators as well as flexible
Circuit breakers V fuses
+ detect a surge in current and break the circuit by opening a switch
+ can be reset by putting the switch back in place unlike a fuse which melts and has to be replaced
- more expensive