Hi,
im a student doing my physics coursework going towards my a level

i have to put the cold junction of a thermocouple into a beaker of iced water and the hot junction of the thermocouple into a beaker of 100degree c water

I have found that the voltage is so small i am in need of an amplifier (*200)

when i put both of the junctions into the cold beaker i get a readin of 0.4V and when i put both the ends in the hot beaker i get a negative value of -140mV

Can someone explain this to me as none of my physics masters can find a reason for this and i have been told that at the same temperature the thermocouple should read 0.0

greatly appreciated

Adam Paigge

 

Hello,

It is right that the output voltage is low ( milivolt range ).
Here is a page from thr EDUCYPEDIA on thermocouples.
http://www.educypedia.be/electronics/thermocouple.htm

Greetings,
Bertus