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Question
The electrical resistivities of four materials P, Q, R and S are given below:
| P | `6.84xx10^8`Ωm |
| Q | `1.70xx10^8`Ωm |
| R | ` 1.0xx10^15`Ωm |
| s | `11.0xx10^-7`Ωm |
Which material will you use for making: (a) heating element of electric iron (b) connecting wires of electric iron (c) covering of connecting wires? Give reason for your choice in each case.
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Solution
Material S will be used for making the heating element of an electric iron as it has a high resistivity .
Material Q will be used for making the connecting wires of an electric iron as it has a low resistivity
Material R will be used for making the covering of the connecting wires as it has an extremely high resistivity.
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