Question

The electrical resistivity of three materials A, B and C at 20°C is given below :

Material	Resistivity (\(\Omega\)m)
A	\(10^{17}\)
B	\(44\times10^{-6}\)
C	\(1.62\times10^{-8}\)

(i) Classify these materials as conductor, alloy and insulator.

(ii) Give one example of each of these materials and state one use of each material in the design of an electrical appliance say an electric stove or an electric iron. 

Answer 1

The resistivity of the three materials A, B and C are 10¹⁷\(\Omega\)m, 44 × 10^–6 \(\Omega\)m and 1.62 × 10^–8 \(\Omega\)m respectively.

(i)

Material	Resistivity	Type
A	\(10^{17}\Omega m\)	Insulator
B	\(44\times10^{-6}\Omega m \)	Alloy
C	\(1.62\times10^{-8}\Omega m\)	Conductor

(ii) Example of insulator: Rubber 

Uses: Coating of electrical wires 

Example of conductor: Tungsten 

Uses: Tungsten is used as the filament of an electric bulb. 

Example of alloy: Nichrome 

Uses: The heating element of an electric iron