1.

The thermo emf E of a thermocouple is found to vary wit temperature T of the junction (cold junction is `0^(@)C`) as `E=40T-(T^(2))/(20)` The temperature of inversion for the thermocouple isA. `20^(@)C`B. `400^(@)C`C. `-200^(@)C`D. `-100^(@)C`

Answer» Correct Answer - C
`E=40t+(1)/(10)t^(2)`
At inversion temperature E will be minimum
i.e. `(dE)/(dt)=0`
`(d)/(dt)[40t+ (1)/(10) t^(2)]=0`
`:.t=-200^(@)C`.


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