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Above neutral temperature, thermo e.m.f....

Above neutral temperature, thermo e.m.f. in a thermocouple

A

decreases with rise in temperature

B

increases with rise in temperature

C

remains constant

D

changes sign.

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The true statement for thermo e.m.f . of a thermocouple

Near room temperature , the thermo emf of a thermo couple is 40 muV per degree. A galvanometer of 25 Omega and capable of detecting current of the order of 4 mu A is used. Calcualate the smallest temperature difference that can be detected with this galvanometer.

Assertion : When temperature of cold junction of a thermocouple is lowered, the value of neutral temperature of this thermocouple is raised. Reason : When the difference of temperature of two junction is raised, more thermo e.m.f. is produced.

Assertion: When temperature of cold junction of a thermocouple is lowered, the value of neutral temperature of this thermo couple is raised. Reason: When the difference of temperature of two junction is raised. More thermo emf is produced.

Assertion : Neutral temperature of a thermocouple does not depend upon temperature of cold junction. Reason : Its value is constant for the given metals of the couple.

The neutral temperature of a thermocouple is 350^(@)C when the cold junction is at . 0^(@)C When the cold junction is immersed in a bath of 30^(@)C , the inversion temperature is

The emf in a lead-iron thermocouple , one junction of which is at t^(@)C is given by varepsilon=178t-2.4t^(2)( "in "muV) where t is the temperature in .^(@)C .Find the neutral temperature , Peltier coefficient and Thomson coefficient.

The rate of increase of thermo-emf with temperature at the neutral temperature of a thermocouple

Assertion : Thermocouple acts as a heat engine. Reason : When two junctions of thermocouple are at different temperature, thermo e.m.f. is produced.

The thermo e.m.f E in volts of a certain thermocouple is found to very with temperature difference theta in ""^(@)C between the two junctions according to the relation E = 30 theta - (theta^(2))/(15) . The neutral temperatur e for the thermo - couple will be .

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