why is earthing wire generally connected to the appliances' metallic case??
Answers
This is because when the live wire of an faulty appliance comes in contact with the metallic case of the appliance (which happens because of removal of insulating layer like paint from the metallic case due to constant use), the appliance acquires the high potential of the live wire. Now if a person touches this appliance he is bound to get a heavy shock as current flows through his body to the earth.
whereas if the metallic case is earthed then the whole of the current is passed to the earth and the fuse connected to the appliance blows off and gets disconnected. So by doing so you prevented yourself from getting a shock as well as saved the appliance from further damage
Explanation:
specific resistance ≅ Resistivity (f) depends on
the material of the wire and as according
to the question both wires are of same
material ⇒ resistivity of both wires is same.