Question

The rate of increase of thermo e.m.f with temperature at the neutral temperature of a thermocouple
(1) is negative
(2) is positive
(3) is zero
(4) depends upon the choice of the two materials of thermocouple
answer is (3) zero
but HOW???? please explain

Answer 1

Answer:

answer is zero because Thermo-emf with temperature at the neutral point of a thermocouple is maximum.

So, rate of increasing thermo-emf with temperature at the neutral point of a thermocouple is zero.

Answer 2

The rate of increase of thermo e.m.f with temperature at the neutral temperature of a thermocouple is zero.

Option (3) is correct.

Explanation:

• The rate of increase of thermo e.m.f with temperature at the neutral temperature of a thermocouple is zero.
• The value of thermo emf "e" = at + bt^2
• Means temperature and emf are co-related.
• Whe the value of dt / de = 0
• The temperature at this point is known as neutral temperature.
• a + 2bt = 0
• t = -  2 / ab  [ Neutral temperature]