Measure the thermal conductivity of Copper using the Searle's bar method.
This experiment uses steam heating. Be careful to avoid touching the hot surfaces of the steam generator, tubing and the Searle's bar apparatus. Make sure that the steam outlet tube from the apparatus goes to a sink.
Constant-head apparatus, measuring cylinder, stop watch, Searle's apparatus, steam generator, four thermometers T1, T2, T3, T4, Vernier callipers.
T1 and T2 measure the temperature at points on the bar, T3 and T4 measure the temperature of water entering and leaving the spiral C.
Assuming no loss of heat along the bar, it can be shown that:
Q is the heat supplied to the bar in time t,
A is the cross-sectional area of the bar,
dT is the difference in temperature between two points in the bar dx apart,
k is the coefficient of thermal conductivity of the bar.
The heat Q warms up a mass m (in kilograms) of water from temperature T4 to T3 according to the formula:
where c is the specific heat capacity of water (c = 4190 J kg-1 K-1).
Using: , (d in metres), and (A in metres squared) we obtain:
Calculate k and the error in k - see below.
Quote your final result for the thermal conductivity as k k with appropriate units.
© Mark Davison, 1997, give feedback or ask questions about this experiment.Back to the experiment menu