(N/A) Newton's law of cooling states that the rate of loss of heat is directly proportional to the difference in temperature between the body and its surroundings.
To verify this,an experimental setup is used consisting of a double-walled vessel $(V)$ containing water between the two walls to maintain a constant surrounding temperature.
$A$ copper calorimeter $(C)$ containing hot water is placed inside the double-walled vessel. The calorimeter is closed tightly with a cork having two holes.
Two thermometers are inserted through the corks to measure the temperature $T_{2}$ of the water in the calorimeter and the temperature $T_{1}$ of the water in the double-walled vessel,respectively.
The temperature of the hot water in the calorimeter is recorded at equal intervals of time. $A$ graph is plotted between $\log_{e}(T_{2} - T_{1})$ and time $(t)$.
The nature of the graph is observed to be a straight line with a negative slope,which confirms the relation $\log_{e}(T_{2} - T_{1}) = -Kt + C$,analogous to the linear equation $y = -mx + c$.