JAMB - Physics (2004 - No. 17)
Electrical appliances at home are normally earthed so that?
the appliances are maintained at a lower p.d than the earth
both the a.c and d.c sources can be used
a person touching the appliances is safe from electric shock
the appliances are maintained at a higher p.d than the earth
解释
Earthing is used to protect you from an electric shock. It does this by providing a path (a protective conductor) for a fault current to flow to earth. It also causes the protective device (either a circuit-breaker or fuse) to switch off the electric current to the circuit that has the fault.