(a) what is menat by the heating effect of current ? State three factors on which the heat produced in a wire by an electric current depends.
(b) Explain why, through the heating element of an electric heater glows, but its connecting cord does not l glow.
( c) An electric geyser of resistance `20 Omega` takes a current of 5 A. calculate the heat produced in 2 minutes.
(d) Name the commercial unit of electric energy. How many joules are equal to this unit ?