======Radiometer======


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**Materials: **{{$demo.materials_description}}\\
**Difficulty: **{{$demo.difficulty_description}}\\
**Safety: **{{$demo.safety_description}}\\
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**Categories:** {{$demo.categories}}
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**Alternative titles:** Light Energy to Motion
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====Summary====                   
{{$demo.summary}}



====Procedure====  
  - Place a radiometer under a bright lamp or in direct sunlight.  
  - Observe the vanes spinning inside the glass bulb.  
  - Adjust the distance of the light source to see how brightness affects the speed.



====Links==== 
The Radiometer - See the Energy of Light! - Arbor Scientific: 
{{youtube>I4sIU2YWzeA?}}\\

How a Crookes radiometer works - Applied Science
: 
{{youtube>r7NEI_C9Yh0?}}\\

📄 Radiometer - Science World: [[https://www.scienceworld.ca/resource/radiometer/]]\\


====Variations====
  * Compare sunlight vs. artificial light.  
  * Test different lamp intensities or LED vs. incandescent bulbs.  
  * Record spin rates at different distances from the lamp.  
  * Use colored filters to see how wavelength affects energy absorption.



====Safety Precautions====
  * Handle radiometer carefully – the glass bulb is fragile.  
  * Avoid using excessively hot lamps too close to the bulb to prevent overheating.  
  * Supervise students when using electrical lamps.




====Questions to Consider====
  * What role does the partial vacuum play in the radiometer?  
  * Why do the black sides heat up more than the white sides?  
  * What would happen if both sides of the vanes were the same color?  
  * How does this demonstration connect to everyday experiences, like wearing dark vs. light clothing in the sun?