Question

A thermocouple produces a thermoemf of $50\mu V{/}^{0}C$ ,when the two junctions are ${30}^{0}C$ , ${50}^{0}C$ . If the thermoemf generated in the thermopile is 100mV , the number of such thermocouples used are

• A. 50
• B. 75
• C. 100
• D. 150

Answer 1

The correct option is C 100

We have emf for one couple as $50\mu V{/}^{o}C$
In a thermopile, thermocouples are joined in series so emf for n couple is $50n$the temperature differnce is given as $\Delta T={20}^{o}C$and total emf is given as 100mV=100000 V.
Thus we get $50n\times 20=100000V$
or
$n=100$