Q. A thermocouple uses Bismuth and Tellurium as the dissimilar metals. The sensitivity of bismuth is $- 72\mu\ V/℃$ and that of the tellurium is $500\mu\ V/℃.$ If the difference between hot and cold junction is $100℃,$ then the maximum output will be
A) $50\ mV$
B) $7.2\ mV$
C) $42.8\ mV$
D) $57.2\ mV$
Explanation
(d) The sensitivity of the thermocouple will be
$= 500\mu V/℃ - ( - 72\mu V/℃) = 572\mu V/℃$
Therefore for a $100℃$ temperature difference, the thermo $e$.m.f. will be
$E = 572 \times 10^{- 6} \times 100(volt) = 57.2 \times 10^{- 3} = 57.2\ mV$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.