1.

The resistance of a copper wire and an iron at `20^@C` are `4.1 Omega` and `3.9Omega` respectively. Neglecting any thermal expansion, find the temperature at which resistane of both are equal. `alpha_(Cu)=4.0xx10^-3K^-1` an `alpha_(Fe)=5.0xx10^-3K^-1`

Answer» Correct Answer - C
`4.1[1+4.0x10^-3(theta-20)]`
`=3.9[1+5.0xx10^-3(theta-20)]`
solving we get
`theta~~85^@C`


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