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Showing posts from July, 2015

Direct Current Short Questions

           1.    Why do we use connecting wires made of copper? 2.       A wire carrying current remains electrically neutral. Why? 3.       A large number of free electrons are present in metals. Why is there no current in the absence of electric field across it? 4.       Why do electrons acquire a steady drift velocity after applying a voltage? 5.       A wire of resistivity ρ is stretched to three times its length. What will be its new resistivity? 6.       Name any two physical parameters on which the resistivity of the material depends? 7.       Manganin and constantans are used for making standard resistors. Why? 8.       Two wires of equal length, one of copper and other manganin, have equal resistance. Which wire is thicker? 9.       Why is it dangerous to operate electrical appliances with wet hands? 10.    What is the effect of heating a conductor on the drift velocity of free electrons? 11.    Is it possible to make the resistance of metals equal to zer