Question

stuck on these 2 questions

1. A resistor made of Nichrome wire is used in an application where its resistance cannot change more than 2.53% from its value at 20.0°C. What is the highest temperature at which this resistor can be reliably used? The temperature coefficient of resistivity for Nichrome is 0.4 ✕ 10⁻³ (°C)⁻¹.

2. An electronic device designed to operate at any temperature in the range from −9.9°C to 78.7°C contains pure carbon resistors. What is the percent difference in resistance over this range? The temperature coefficient of resistivity for carbon is −0.500 ✕ 10-3/°C.

Answer 1

2.53% 4ivenchange Henes, fraetimal change in esistance 2.53 R- 7 Resistance ofwie with given vaxymg as temperature R temperature Resistance at T Ri sde Sultraet ng beth 7 R& R-Ri Ri' 4 7 AR - 3 63.25

63.25 7p- 7 3.25t 20 Tp 83.25 'c Highest temperature of resis ter vesistance =2.53 - ehamge (fot Maxmwm 3.25 c 7f PART 2 Given - 9.g'c T2 -3 xlo 25'C temperature Ro (1 4T) (71-T) 7 et RI Hence R2 8.7) R and 72 -T - Divideng eguation i)

!t (7, - 7) Ki (-9.90 78 (-9.9-25 /+SA39.7- 25 -3 1.01y5 R2 0.973/5 Sub tvacting () bth sol R2 Ri-Ri R2 0.oy5 0.0y R2 7esistana en ce 4.5 /