What is the percentage change in the resistance of german-silver wire when its temperature changes from 25 degree celsius to 50 degree celsius , alpha equals 0.0004 per degree celsius

Asked by Shashank | 15th Nov, 2014, 07:29: PM

Expert Answer:

We know that resistance of pure metals increases with rise in temperature.Let R0 be the initial resistance at T0 = 25°C and R be the resistance at T =50° C
Let α be the temperature coefficient of resistance and =0.0004 /°C
We know that R = R[1 + α (T - T0) ]
Change in temperature, ΔT = 50°C - 25°C =25 °C
begin mathsize 14px style Fractional space change space in space resistance space can space be space written space as : space fraction numerator straight R minus straight R subscript 0 over denominator straight R subscript 0 end fraction equals αΔT fraction numerator straight R minus straight R subscript 0 over denominator straight R subscript 0 end fraction equals 0.0004 divided by degree straight C space cross times space 25 space degree straight C fraction numerator straight R minus straight R subscript 0 over denominator straight R subscript 0 end fraction equals 0.01 Percentage space change space in space resistance space equals space 0.01 cross times 100 space equals 1 space Percentage end style 

Answered by Jyothi Nair | 15th Nov, 2014, 08:37: PM