Physics Flashcards
What does AC mean?
Alternating current, which means the current changes direction
Mains supply is…
AC
Battery supply is…
DC
What does DC mean?
Direct current, which means the current flows in the same direction
What is the UK mains supply approximately in volts?
230 volts
What do you divide the time period by to work out the frequency?
1
Name 7 hazards about electricity…
Long cables Frayed cables Damaged plugs Shoving things into sockets Too many plugs in 1 socket Appliances with no covers Lightning sockets without bulbs in
What are the colours for the live, neutral & earth wires?
Brown, blue & green/yellow
Name 6 safety features of a plug…
Right coloured wire in each pin Firmly screwed in No bare wires showing Cable grip tightly fastened Copper/brass - good conductors Case/cable grip/cable insulation made of rubber/plastic - good insulators & flexible
What do fuses and earthing prevent?
Electrical overloads.
The larger the current, the ________ the cable you need to carry it.
Thicker.
Describe the 5 stages when a fault develops…
- FAULT - Live wire touches the metal case.
- Current flows from the live wire to the earth wire. The earth wire is connected to the metal casing, so it’s earthed.
- Current surges to earth.
- The surge in the current melts the fuse. So cuts off the live supply and breaks the circuit.
- The appliance is then isolated from the live wire. It makes it impossible to receive an electric shock from the case and also prevents a fire.
What are circuit breakers?
Circuit breakers are an electrical safety device in circuits. They are used to protect the circuit from damage if too much current flows.
Why are circuit breakers better than fuses?
- Operate faster.
* Reset by flicking the switch, unlike fuses you have to replace.
How are circuit breakers used?
A circuit breaker detect a surge and break the circuit by opening a switch.
