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(a) State Fleming’s Left-hand rule.(b) List three characteristic features of the electric current used in our homes.(c) What is a fuse? Why is it called a safety device?(d) Why is it necessary to earth metallic electric appliances?
(a) Fleming's left-hand rule: When left hand's thumb, forefinger (or, index finger) and centre finger (or, middle finger) are held mutually perpendicular to one another and adjust in such a way that the forefinger points in the direction of the magnetic field, and the centre finger points in the direction of the current, then the direction in which thumb points, gives the direction of force acting on the
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(b) Three characteristic features of the electric current used in our homes are:
1. Appliances to be connected in parallel.
2. Each appliances has a separate switch to ON/Off the flow of current through it.
3. Potential difference between live wire and neutral wire is about 220V.
(c) Fuse is a safety device used in a circuit (or appliance) to automatically cut off the electricity supply during overloading/short circuiting, so that home appliances can be prevented from the damage.
It is called a safety device because, it protects the circuit (or appliance) by stopping the flow of any unduly high electric current. If current larger than the specified value flows through the circuit, then the fuse wire melts and breaks the circuit.
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(d) It is necessary to earth metallic electric appliances because it provides a low resistance conducting path for the current and protects the user from fatal electric shock due to insulation failure or accidental short circuit.
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