Overview
The Emissivity Measurement Apparatus determines the emissivity of various surfaces by comparing their thermal radiation output with that of a reference black body surface under identical conditions. Two identical plates, one treated as a black body (painted matt black) and one with the test surface finish, are heated to the same temperature in a radiation-shielded enclosure. Students calculate the emissivity ratio from the net radiative heat loss of each surface using the Stefan-Boltzmann law. The apparatus demonstrates the importance of surface characteristics in radiative heat transfer and is relevant to thermal insulation, spacecraft thermal control, and industrial furnace design.
Specifications
| Test surfaces | polished, painted, oxidised metal |
| Reference surface | matt black body coating |
| Heater | electric cartridge, 0 to 200W per plate |
| Temperature range | ambient to 300 degrees C |
| Temperature sensors | thermocouples, 2 per plate |
| Enclosure | radiation-shielded aluminium chamber |
| Temperature controller | PID auto-control |
| Power supply | 220V AC, 50 Hz |