Why does the cord of an electric heater not glow while the heating element does ?

(a) What is meant by saying that the potential difference two points is 1 volt ? Name a device that helps to measure the potential difference across a conductor. (b) Why does the connecting cord of an electric heater not glow hot while the heating element does ? ( c) Electrical resistivities of some substances at 20^@ C are given below : Silver 1.60 xx 10^-8 Omega m Copper 1.62 xx 10^-8 Omega m Tungsten 5.20 xx 10^-8 Omega m Iron 10.0 xx 10^-8 Omega m Mercury 94.0 xx 10^-8 Omega m Nichrome 100 xx 10^-6 Omega m . Answer the following question in relation to them : (i) Among silver and copper, which one is a better conductor ? Why ? (ii) Which material would you advise to be used in electrical heating devices ? Why ?

Element of an electric heater is made of which of the following metals ?

(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 ?

Why does zinc oxide exhibit enhanced electrical conducity on heating ?