(i) Calculate the current through a lamp of 25 W operating at 250 V. (ii) Why elements of electrical heating devices are made up of alloys?
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(i) Power of the lamp, P = 25 W Potential difference, V = 250 V Current, I = ? Formula `=VxxI" "therefore " "25=250xxI` `therefore "Current", I =(25)/(250)=(1)/(10)=0.1 A` (ii) The heating elements of electrical heating appliances are made up of nichrome alloy because: nichrome has very high resistivity due to which it produces a lot fo heat on passing current. nichrome does not undergo oxidation easily even at high temperature, it can be kept red hot without burning.
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