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A thermocouple-based temperature measurement system is shown in the adjoining figure. Relevant thermocouple emf data (in mV) is given below. The cold junction is kept at 0°C. The temperature is 30°C in the other parts of the system. The emf V is measured to be 26.74 mV. Th temperature of the hot liquid is Temp. emf of Chromel- Constantan emf of Copper- Constantan 10°C 0.591 0.391 20°C 1.192 0.789 30°C 1.801 1.196 370°C 26.549 19.027 380°C 27.345 19.638

A thermocouple-based temperature measurement system is shown in the adjoining figure. Relevant thermocouple emf data (in mV) is given below. The cold junction is kept at 0°C. The temperature is 30°C in the other parts of the system. The emf V is measured to be 26.74 mV. Th temperature of the hot liquid is Temp. emf of Chromel- Constantan emf of Copper- Constantan 10°C 0.591 0.391 20°C 1.192 0.789 30°C 1.801 1.196 370°C 26.549 19.027 380°C 27.345 19.638 Correct Answer 380.0°C

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As junctions band C formed with similar type of metals,

VB = 0

VC = 0

VA = V(Chromel – constantan) - V(Copper – Constantan)

From the given data, at 30°C.

VA = 1.801 – 1.196 = 0.605 mV

Now, VO = VHot – 0.605

Given that,

VO = 26.74 mV

⇒ VHot = 26.74 + 0.605 = 27.345 mV

Hot junction is made up of chromel-constantan

From the given data

27.345 mV is corresponding to 380°C

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