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The temperature of inversion of a thermo...

The temperature of inversion of a thermocouple is `620^(@)C` and the neutral temperature is `300^(@)C`. What is the temperature of cold junction?

A

`40^(@)C`

B

`20^(@)C`

C

`320^(@)C`

D

`-20^(@)C`

Text Solution

Verified by Experts

Let `e=alpha(theta-theta_(c))+beta(theta^(2)-theta_(c)^(2))`
where `theta_(c)=` temperature of cold junction.
at inversion temperature `e=0rArr theta_(i)=- theta_(c).-(alpha)/(beta)`
at neutral temperature `(de)/(d theta)=0`
`rArr theta_(n)=-(alpha)/(2beta)`
`rArr theta_(i)=-(alpha)/(beta)-theta_(c)=2theta_(n)-theta_(c)rArr theta_(n)=(theta_(i)+theta_(c))/(2)`
`rArr300=(620+theta_(c))/(2) rArr theta_(c)=-20^(@)C`
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