Question 37 of 215

The thermo emf E in volt of a certain thermo-couple is found to vary with temperature difference θ in °C between the two junctions according to the relation 

                               E=30 θ-θ215

The neutral temperature for the thermo-couple will be 

(a) 450°C                                          (b) 400°C

(c) 225°C                                           (d) 30°C