E=aθ+bθ2 At neutral temperature dE/dθ=0 ∴dθdE=a+2 bθn=0;θn=−2 ba Now ba=700∘C (given) θn=−700/2=−350∘C Now θc=0∘C. So, θn>0∘C But mathematically θn<0∘C.
JEE Main 2004 — Physics Thermodynamics
The thermo emf of a thermocouple varies with the temperature θ of the hot junction as E=aθ+bθ2 in volts where the ratio a/b is 700∘C. If the cold junction is kept at 0∘C, then the neutral temperature is
Held on 30 Apr 2004 · Verified 6 Jul 2026.
700∘C
350∘C
1400∘C
no neutral temperature is possible for this thermocouple.
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