Advertisements
Advertisements
प्रश्न
How does earthing prevent electrical shock?
Advertisements
उत्तर
Local earthing provides us safety from electric shocking in the case of short circuiting. When excessive current flows through the live wire, it will pass to the earth through the earth wire. In the absence of local earthing, it may causes fire due to over heating of the live wire.
In the case of an electronic appliance, if its outer metallic body is earthed and by chance, if it happens to touch live wire, then metallic casing acquires the potential of the live wire and so any person touching it is likely to get a total shock. But if earthed, a heavy current flows and the fuse connected to the appliances blows off. Thus the person touching it does not get any shock.
संबंधित प्रश्न
Why is an electric light bulb not filled with air? Explain why argon or nitrogen is filled in an electric bulb.
Electrical power P is given by the expression P = (Q × V) ÷ time. What do the symbols Q and V represent?
Name the S.I. unit of electrical energy. How is it related to Wh?
Water in an electric kettle connected to a 220 V supply took 5 minutes to reach its boiling point. How long would it have taken if the supply voltage had fallen to 200 V?
A resistor of resistance R is connected to an ideal battery. If the value of R is decreased, the power dissipated in the resistor will ______________ .
An electric bulb, when connected across a power supply of 220 V, consumes a power of 60 W. If the supply drops to 180 V, what will be the power consumed? If the supply is suddenly increased to 240 V, what will be the power consumed?
Why is heating element wound on a long porcelain rod in a room heater.
Two lamps are rated 220V, 50W and the other rated 220V, 100W are connected in series with the mains of 220 V. Explain, why the 50W lamp glows more?
Two electric lamps each rating 100 W, 110 V are connected in series to a 220 V power supply and two other electric lamps each of marking 100 W, 220 V are connected in parallel to the same power supply. Will anyone of the two combinations give more light than the other? Give a reason for your answer.
A cooler of 1500 W, 200 volts and a fan of 500 W, 200 volts are to be used from a household supply. The rating of fuse to be used is:
