The temperature cofficient of resistance of a conductor is `0.002//""^@C . " At " 250^@C` , resistance of conductor is `4Omega` , its resistance will be `6Omega` at temperature about

Options

A. `625^@C`
B. 425K
C. 625K
D. 550K

Answer

A

Explanation

`R=R_0(1+alpha Deltat)`
`R_1 = R_0(1+alphaDeltat_1)`
`R_2=R_0(1+alphaDeltat_2)`
`R_1/R_2 = (1+alphaDelta_1)/(1+alphaDelta_2)`
`rArr 4/6=([1+(0.002xx250)])/([1+0.002xxt_2]) = (1.5)/(1+0.002t_2)`
`rArr 1+0.002t_2 = 9/4`
`rArr t_2=5/4xx500=625^@C`