Temperature coefficient of resistance of a material is 0.005Ω/°C. At 0°C, the resistance of a wire made up of this material is 1Ω. At what temperature the resistance will become 2 Ω. 

Concept:

The resistance of conductor changes when the temperature of that conductor changes.

New resistance is given by:

Where Rt = Final resistance or the resistance of the conductor after temperature changes

R0 = Initial resistance or the resistance of the conductor before temperature changes

α = temperature coefficient 

ΔT = final temperature – initial temperature 

Calculation:

Given that

= 1 Ω

α = 0.005 Ω/°C

T1 = 20°C

 =  (1+0.005 * ()}

= 1.1

Now resistance

∴ 2 =  [1 + 0.005 × (T₂ - 20)]

T₂ *  = 

T₂ =240° C