The thermo emf of a thermocouple varies with the temperature θ of the hot junction as E = aθ + bθ2 in volt where the ratio a/b is 700°C. If the cold junction is kept at 0°C, then the neutral temperature is
(a) 700°C
(b) 350°C
(c) 1400°C
(d) no neutral temperature is possible for this thermocouple.
