Description
The radiometer is a fascinating example of heat exchange causing movement. Originally developed in the mid-nineteenth century by Sir William Crookes, the bulb has nearly 99% of the air removed making the air molecules able to move about more easily.
- Inside the bulb are 4 diamond-shaped flags connected in a cross that can freely spin on a needlepoint.
- Each flag has a white side and a black side.
The radiometer works due to air expanding more rapidly over hot surfaces compared to cold surfaces.
- When you place the radiometer in the sun (or point a spotlight towards it), the heat from the infra-red light gets absorbed by the black side of the flag.
- This causes the air next to the black side of the flag to expand, which pushes the flag and make its spin.
- The same thing happens to the next flag that is near the heat source
- … & so on!
NB: If using a spotlight, only keep it pointed at the radiometer for a limited amount of time, otherwise you could melt the plastic base.
Teaching ideas for a Crookes radiometer
- Conduct this balloon experiment that shows that air expands when heated.
- Learn more about Charles’s Law
- Try fluorescent lights vs incandescent lights on the radiometer. Is there a difference?
- Discuss kinetic vs potential energy
School science visit that expands on this science teaching resource
I just wanted to pass on how much the staff and students really enjoyed it and how perfect it was to launch our science week activities. The students were enthralled, educated and entertained – a perfect trifecta!
-Caulfield Grammar School – Big Science Big FunThanks so much for presenting at our school on Monday. Our students enjoyed the show.
-Greenvale Primary School – Big Science Big FunFizzics Education curated a thoughtful and hands-on experience for the children, incorporating practical, skill-based learning activities and followed by a science presentation at the end of the event involving liquid nitrogen. This was delivered safely and effectively, capturing both the children and the parents for the duration of the presentation.
-Macquarie Bank – Family Fun DayFizzics Education ran a show today at our school and it was wonderful. He was a great facilitator and the show was age appropriate and well done.
-Mount Zion Early learning centre – Little Science Big FunI just wanted to pass on how much the staff and students really enjoyed it and how perfect it was to launch our science week activities. The students were enthralled, educated and entertained – a perfect trifecta!
-Caulfield Grammar School – Big Science Big FunThanks so much for presenting at our school on Monday. Our students enjoyed the show.
-Greenvale Primary School – Big Science Big FunFizzics Education curated a thoughtful and hands-on experience for the children, incorporating practical, skill-based learning activities and followed by a science presentation at the end of the event involving liquid nitrogen. This was delivered safely and effectively, capturing both the children and the parents for the duration of the presentation.
-Macquarie Bank – Family Fun DayFizzics Education ran a show today at our school and it was wonderful. He was a great facilitator and the show was age appropriate and well done.
-Mount Zion Early learning centre – Little Science Big Fun