Why are coils of electric toasters and electric irons made of an alloy rather than a pure metal?

Solution:

The melting point of an alloy is much higher than a pure metal because of its high resistivity. At high temperatures, alloys do not melt readily. Therefore, alloys are used in heating appliances such as electric toasters and electric irons.

1. Use the data in the table given below and answer the following questions.

Material	Resistivity
Conductors	Silver	1.60 × 10–8
	Copper	1.62 × 10–8
	Aluminium	2.63 × 10–8
	Tungsten	5.20 × 10–8
	Nickel	6.84 × 10–8
	Iron	10.0 × 10–8
	Chromium	12.9 × 10–8
	Mercury	94.0 × 10–8
	Manganese	1.84 × 10–6
Alloys	Constantan	49 × 10–6
	Manganin	44 × 10–6
	Nichrome	100 × 10–6
Insulators	Glass	1010 – 1014
	Hard rubber	1013 – 1016
	Ebonite	1015 – 1017
	Diamond	1012 – 1013
	Paper (dry)	1012

1. Which among iron and mercury is a better conductor?
2. Which material is the best conductor?

Solution:

1. Iron is a better conductor than mercury because the resistivity of mercury is more than the resistivity of iron.
2. Among all the materials listed in the table, silver is the best conductor because the resistivity of silver is lowest among all, i.e., 1.60 × 10^–8.