In our homes, we receive the supply of electric power through a main supply also called mains, either supported through overhead electric poles or by underground cables. In our country the potential difference between the two wires (live wire and neutral wire) of this supply is 220 V.
Earthing wire in domestic electric circuits is a safety measure. Justify this statement explaining its role in case of accidental leakage of electric appliances.
Define electric power. Derive the expression P = I²R and P = V²/R. An electric iron consumes 1000 W when operated at 220 V. Calculate the current and the resistance of the iron. Also, State two safety precautions to be taken while handling electrical appliances.
With the help of a ray diagram, explain the formation of an image by a convex lens when the object is placed — (a) at infinity, (b) between F and 2F, (c) at F. State the nature, position, and size of each image.
Before cleaning the light bulb in his room, Gautam turned off the light by turning the switch off. Yet, he received an electric shock while cleaning the bulb. Explain why the bulb connection was live though the switch was off.
The picture below shows two diagrams of the wiring of an electric clothes iron. The thermostat is a device that can be set at a particular temperature, and controls the heating temperature of the iron by automatically shutting off and on. The indicator light is connected differently in the two diagrams. (a) Explain how the difference in the connections affects the functioning of the indicator light. (b) Does this difference change the heating of the iron? Justify your answer. (c) State the function of the earthing wire.
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