Thermocouple temperature measurement I know that different materials have a different specific heat capacity and $$Q=mc\Delta T$$
Does this mean a thermocouple can only measure its own temperature and not the temperature of e.g. a metal surface? So the surface of a metal would have a different temperature? 
 A: Temperature is defined by the zeroth law of thermodynamics, which states that 

Given any three bodies, $A$, $B$ and $C$, if, when brought into thermal contact, $A$ is found to be in thermodynamic equilibrium with $B$ and if when $B$ is brought into thermal contact with $C$ they are found to be in thermodynamic equilibrium then $A$ is in thermodynamic equilibrium with $C$. In this case the bodies are said to have the same temperature.

In other words if 2 objects are in thermal contact but no heat is flowing between them, they have the same temperature.
This means that, although the thermocouple can only directly measure its own temperature, if you put it in contact with, say, a metal plate and wait for them to reach thermodynamic equilibrium the plate and the thermocouple will have the same temperature by definition and so you can measure the metal plate's temperature by looking at the thermocouple. The heat capacity of the thermocouple simply never enters into the question.*
*There is a practical caveat that this is assuming that the heat capacity of the thermocouple is much  less than the heat capacity of the thing you are trying to measure. If this is not the case then the amount of heat transfer needed to bring the thermocouple to the same temperature as the system will significantly alter the temperature of the system, so you are no longer measuring its original temperature. 
A: Thank you everyone for the answers.  :D
So my conclusion is that the temperature will eventually even out (zeroth law of thermodynamics) and it will draw whatever amount of heat energy in accord to Q=mc(dT) and will continue to draw heat energy until there's no temperature gradient. Depending on how close or the compression applied between the 2 objects the heat transfer per second may vary due to thermal contact resistance at micro level. Also, as long as the thermocouple does not draw a significant amount of heat (e.g. due to the mass or the specific heat capacity of the thermocouple) it will not change the temperature distribution of the system that's being measured.
A: Thermocouples meassure their own temperature. If you make a good contact between measured item and thermocouple, the temperature between them will be similar. As soon as the temperature of the measured item changes, the temperature shown by hermocouple will be incorrect.
If you want to meassure the temperature of the measured item, you have to use technology like IR sensors which detect the actual temperature of measured object.
