Thermal conductivity of a Bad conductor using Lee's method

AIM: To determine the thermal conductivity of bad conductors such as card board, ebonite, etc.

Apparatus:

1. Lee's disc apparatus
   
2. a brass disc and a metallic disc of large diameter compared to its thickness
   
3. sample of bad conductor in the form of the disc with same diameter
   
4. two mercury thermometers
   
5. stop watch
   
6. vernier
   
7. screw gauge and
   
8. a balance.