Introduction

Angstrom developed a method of determining the thermal conductivity of a metal rod by applying an alternating heat pulse to one end while leaving the other end at room temperature. Doing this causes a heat wave to propagate down the rod and creates an observable temperature difference between two points on the rod. This also creates a varying phase relationship between the measured temperature recorded at the first and second points.The thermal conductivity of the rod can be determined if the temperature of these two points is measured as a function of time.

PROCEDURE

Part of the heat traveling down the length of the rod will be transmitted through conduction, part will heat the rod itself, and part of the heat will be lost to the air through radiation. The following theory follows the development given in Advanced Practical Physics by Worsnop and Flint.

Thermal conductivity is defined through the rate of heat energy lost through the surface of some object.

CONSTRUCTION

A Copper rod 25 mm dia x 250 mm long having three holes 12 mm deep at a distance of 50 mm from one end for Probes and the other side is having a                                   hole for  heating element. Heating an 25 watt element with power supply is fitted at other end mains operated 220V AC 50 Hz. Having                                  A lead and shoe

WOODEN BOX The copper rod is fitted on a wooden base having a rectangular removable box open from one side and having holes at TOP for heating                                     sensors.

SENSORS         Two probes ( with thermistors at end) are provided to be inserted into the copper rod and both are connected to a Data Analyzer which                                  displays the temperature of the copper rod periodically.

DATA ANALYZER it records the temperature of the copper rod periodically and makes a Graph temperature verses time , directly on the display SCREEN 3.5                                      inches. You can click the photograph of the result displayed on the screen or plot a graph on the paper.