CBSE Class 10 Science 2020 · Paper 31(B) · Question 24

Overloading: the appliances connected to a circuit draw more current than it is designed to carry. It is caused by connecting too many appliances to a single socket, or by an accidental hike in the supply voltage, and the excess current overheats the wires. Short-circuiting: the live wire and the neutral wire come into direct contact (for example, when the insulation is damaged or an appliance is faulty). The resistance of the circuit becomes very small, so the current in the circuit abruptly increases to a very large value. Earth wire: it connects the metallic body of an appliance to a metal plate buried deep in the earth and provides a low-resistance conducting path for the current. Any current that leaks to the metal body flows to the earth, so the body stays at the potential of the earth and the user does not get a severe electric shock.