Investigating infrared radiation
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Explainer Video
Summary
Investigating infrared radiation
In a nutshell
By filling a Leslie cube with water, the infrared intensity of the cube's different surfaces over time will be measured using a infrared detector. This corresponds to the amount of infrared radiation radiated by the surfaces of the cube.
Equipment list
The following equipment list can be used to conduct the experiment to investigate infrared radiation radiated.
Equipment | Use |
| Leslie cube (a cube with different surfaces) | To show the thermal radiation radiated by different surface. |
| Infrared detector | To measure the infrared radiation given off by the surfaces. |
| Kettle | To boil the water before pouring it in the cube. |
| Heatproof mat | To place the beaker on in order to prevent heat escaping from the bottom of the beaker. |
| Stopwatch | To time the experiment. |
| ruler | To measure the distance between the infrared detector and the side of the Leslie cube. |
Experimental variables
The independent variable is the variable you change. The dependent variable is the variable that changes depending on the other variables, and is the one you measure. The control variables are the variables that are kept constant.
| Independent Variable | |
| Dependent Variable | |
| Control Variables | |
Safety precautions
When performing experiments, it is very important to consider safety precautions. This is so that no one gets hurt or injured during the experiment.
Hazard | Risk | Safety masure |
| Hot water | The water will be near boiling temperature when it is poured into the Leslie cube. This could cause burns if spilt on someone. | Don't rush when pouring the water. If burnt, run the burn under cold running water for five minutes. |
| Water and electronics | Spilled water on the infrared detector may result in an electric shock. | Keep the infrared detector away from water. |
Method
These are the instructions to complete the experiment. Record all measurements taken as you work through the experiment in a table.
 |
|
| 1. | Set up the apparatus as shown in the diagram. Make sure the detector is away from the cube |
| 2. | Boil the kettle. Fill the Leslie cube with the just boiled water. |
| 3. | Leave the Leslie cube for a minute to give the surfaces time to be heated by the water. |
| 4. | Measure the intensity of infrared radiation radiated from each surface using the infrared detector. Tip: If you can find four rulers, you can place these on every side of the cube so you can quickly move the detector to the mark when recording the temperature. |
Analysis
This is how you will use the data recorded to form conclusions.
| 1. | Plot a bar chart of infrared intensity (units of ) for each surface. |
| 2. | Compare the height of the bars to each other with how radiation emitted depends on the surface of an object. A black matte surface emits the most infrared radiation, whilst a shiny silver surface emits the least. |
Conclusion
The bar chart of the results taken during the experiment should look similar to this. The black matte surface should emit the most infrared radiation, followed by the shiny black, white matte then shiny surface.
Evaluation
Once you have completed your experiment, it is important to consider how it could be improved. You should come up with ways to improve the accuracy of your values. If you got a result that seems unreasonable, think about why this was.
FAQs - Frequently Asked Questions
What surface is the best at emitting infrared radiation?
A black matte surface emits the most infrared radiation.
What is the independent variable in the infrared radiation experiment?
The independent variable in the infrared radiation experiment is the side of the Leslie cube being measured.
How do you test for infrared radiation?
By filling a Leslie cube with water, the infrared intensity of the cube's different surfaces over time will be measured using a infrared detector. This corresponds to the amount of infrared radiation radiated by the surfaces of the cube.