A thermocouple is that is attached to a milli-voltmeter which reads 50mV when one junction is immersed in ice and the other is in steam.

What is the temperature of the warm liquid in degree Celsius if the milli-voltmeter reads 34.4mV with one junction in ice and the other junction in the liquid?

Explanation:

thermoelecric emf is proportional to temperature difference of the couple .

E = a T , E is emf due to temperature difference of T .

given T = 100 and emf = 50 mV .

50 = a x 100

a = .5 mV / degree Celsius

E = .5 T

when emf = 34.4 mV , T = ?

Put these values in the equation below

E = .5 T

34.4 = .5 T

T = 68.8 degree Celsius.

So temperature of warm liquid = 68.8 °C.

thermal energy is the answer