<p>Explain the following:</p>

<p>(i) Why is tungsten used almost exclusively for filament of electric lamps?</p>

<p>(ii) Why are the conductors of electric heating devices, such as toasters and electric ions, made of an alloy rather than a pure metal?</p>

<p>(iii) Why is the series arrangement not used for domestic circuits?</p>

<p>(iv) How does the resistance of a wire vary with its area of cross section.</p>

<p>(v) Why are copper and aluminium wires usually used for electricity transmission?</p>