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

Options

(a) is positive
(b) is zero
(c) depends upon the choice of the two materials of the thermocouple
(d) is negative

Correct Answer:

is zero

Explanation:

We have, e = at + bt²
de/ dt = a + 2bt
At neutral temperature,
t = – a / 2b
de/ dt = 0