Photovoltaic Windmills Toy Manufacturer,Supplier and Exporter in India
Product Code : EL-CR-10942
Quick Answer: The Photovoltaic Windmills Toy is a glass radiometer, 75mm in diameter and 80mm high, with four lightweight vanes in a vacuum bulb that spin when light shines on them.
Last updated: October 2026
Key Features
Glass bulb, 75mm diameter and 80mm high
Four vanes suspended inside a glass bulb with a good vacuum
Vanes alternately dark and light in colour
Lighter vanes reflect the light and darker vanes absorb it
Stronger light gives faster spinning
About This Product
Placed near a window or under an incandescent lamp, the vanes turn when light falls on them. The vacuum matters: with air in the bulb there is too much drag for the vanes to spin, while in a good but incomplete vacuum an effect called thermal transpiration at the vane edges makes the black faces move away from the light. It can stand or hang at a window, showing each ray of sunshine as movement.
Frequently Asked Questions
Q1. Why does the radiometer need a vacuum? If the bulb were full of air, the vanes would not spin because of too much drag. The good vacuum inside the bulb lets them turn in light.
Q2. What size is it? It is 75mm in diameter and 80mm high.
