practical electricity 💪 Flashcards
power formulae (x3)
1) P = VI
2) P = I²R (for series where current is constant)
3) P = V² / R (for parallel where pd is constant)
how to convert J into kWh?
1kWh = (1000)(3600) J = 3600000 J
what happens when the insulation of wires are damaged?
exposed wire can cause electric shock when touched. could also result in a short circuit leading to a fire
why do some appliances have thinner wires compared to others?
a thinner wire has a higher resistance and supplies more power to the appliance (also generates more heat)
safety features in household circuits
1) circuit breakers
2) fuses
3) switches
4) earthing
5) three-pin plugs
6) double insulation
what is the advantage of using a circuit breaker over a fuse?
circuit breaker can be reset easily after it trips the circuit, while a fuse has to be replaced
why must the switch / fuse / circuit breaker be connected to the live wire?
to disconnect the appliance from the high voltage
if connected to the neutral wire, the appliance is still connected to the high voltage even if the safety devices are off. user can experience an electric shock if he touches the exposed live section
where is the earth wire connected to?
the metal casing
what is double insulation?
apart from the insulation on the wires, there is an outer casing made of insulating material
