# TH-3105 Thermal and Light Radiation

Experiments

• Inverse Square Law for Heat – To show that the intensity of radiation on a surface is inversely proportional to the square of the distance of the surface from the radiation source.
• Stefan-Boltzmann Law – To show that the intensity of radiation varies as the fourth power of the source temperature.
• Kickoff’s Law – To determine the validity of Kickoff’s Law which states that the emissivity of a grey surface is equal to its absorptivity of radiation received from another surface when in a condition of thermal equilibrium.
• Area Factors – To demonstrate that the exchange of radiant energy from one surface to another is dependent upon their interconnecting geometry, i.e. a function of the amount that each surface can ‘see’ of the other.
• Inverse Square Law for Light – To show that the
• illuminance of a surface is inversely proportional to the square of the distance of the surface from the light source.
• Lambert’s Cosine Law – To show that the energy radiated in any direction at an angle with a surface is equal to the normal radiation multiplied by the cosine of the angle between the direction of radiation and the normal to the surface.
• Lambert’s Law of Absorption – To show that light passing through non-opaque matter is reduced in intensity in proportion to the thickness and absorptivity of the material.
• Determining the emissitivity of radiating surface with different finishes namely polished and gray compared with matt black.
• Demonstrating on how the emissitivity of radiating surface in close proximity to each other will affect the surface temperature and the heat exchanged.
• Demonstrating the exchange of radiant energy from one surface to another is dependent upon their interconnecting geometry for example, a function of the amount that each surface can see of the other.

## Description

The unit has been designed to demonstrate the fundamental laws relating to radiation. By performing a series of simple experiments the students may verify the relevant equation appropriate the behavior of radiations. Thermal radiation is a mode of heat transfer which differs significantly from the other two modes. The fact that radiant energy transfer occurs across a vacuum is often disturbing to students unless the theory relating to properties of electromagnetic waves has been presented. The engineer is not directly concerned with the mechanism by which heat transfer occurs, but a sound knowledge of the properties and laws relating to the topic are required. By performing a series of simple experiments the student may verify the relevant equations of radiation. The unit Thermal Radiation consists of electrically heated radiant heat and light sources together with a comprehensive range of targets and measuring instruments.

Thermal radiation is a mode of heat transfer, which differs significantly from the other two modes, namely conduction and convection. The fact that radiant energy transfer occurs across a vacuum is often disturbing to students unless the theory relating to properties of electromagnetic waves has been presented.

RADIATION HEAT TRANSFER & EXCHANGE consists of a pair of electrically heated radiant heat and light sources, together with a comprehensive range of targets and measuring instrumentation.

The unit has been designed to demonstrate the fundamental laws relating to radiation. By performing a series of simple experiments the student may verify the relevant equation appreciate the behavior of radiation.

The unit consists of a horizontal track fitted with interchangeable heat radiation source end and light source. Either the heat radiation detector or the light meter may be placed on the horizontal track. In addition, a number of accessories can be fitted for experimental purposes. These include metal plates, two vertically orientated metal plates to form an aperture, and a number of light filters. The radiation detectors accessories are all clamped to stand, which enable them to be positioned at different distances from the source. Distances are measured with scales mounted on the front and the back of the track.

Temperatures of the three metal plates used in conjunction with the heat radiation source are displayed on the control panel. Output from heat radiation detector and light meter are displayed on digital read out.

Software TH-3105SW (optional)
DAQ software specially designed in National Instrument™, LABVIEW™ environment to measure and calculate the results of apparatus. The software is optional and while using software a set of electronic sensors are included. Software can be run with any Windows™ environment.