Moe-Ying Solar Glass Windmill (Three Designs Available)

Don't let its simple appearance fool you; this glass sphere houses a classic physics experiment – the "Crookes Radiometer." When exposed to sunlight or strong light, the black and white sides of the vanes create a subtle pressure difference due to variations in light absorption and heat, causing the windmill to spin. This phenomenon is a result of the combined effects of photon momentum (light pressure) and thermal effects, making it a captivating little toy that demonstrates how light can exert a gentle push! https://cdn-next.cybassets.com/s/files/5993/ckeditor/pictures/content_0d593d31-ff34-4e76-98f0-21248a8f3986.jpg https://cdn-next.cybassets.com/s/files/5993/ckeditor/pictures/content_548d3cd9-35c6-42d6-88b4-6173eda43278.JPG Watch butterflies dance in the light, bats circle in the sun, and cats lazily turn – each of the three designs has its own unique charm. The speed of rotation varies with the angle and intensity of the sunlight, as if light itself has come alive. https://cdn-next.cybassets.com/s/files/5993/ckeditor/pictures/content_7ee393f9-83a0-4e43-94e4-df8ae86b76bd.JPG Place it by your window, on your desk, in your office, or on a bookshelf – witnessing it quietly awaken with light and slowly turn is like pausing time for a moment. More than just a decorative piece, it's a daily source of comfort, blending scientific education with artistic beauty. https://cdn-next.cybassets.com/s/files/5993/ckeditor/pictures/content_825bb0e3-523c-477d-a980-fe45cb1edd3d.JPG 🌞 As early as 1873, British scientist William Crookes invented this device to study light pressure and molecular motion. Modern versions typically use a vacuum-sealed glass bulb. The vanes can only rotate due to extremely subtle molecular collisions when in a near-vacuum state. 🚫 Interestingly, it won't move in a "perfect vacuum"! This is because there are no gas molecules to help transfer the thermal difference. https://cdn-next.cybassets.com/s/files/5993/ckeditor/pictures/content_aeb0d20d-2127-48ed-8170-bc90ee081c55.JPG https://cdn-next.cybassets.com/s/files/5993/ckeditor/pictures/content_b9b76a21-fc16-406b-b1b9-b41f08650abc.JPG https://cdn-next.cybassets.com/s/files/5993/ckeditor/pictures/content_11097135-339e-4fdd-8e90-1c1c6e22d868.JPG https://cdn-next.cybassets.com/s/files/5993/ckeditor/pictures/content_01f5e263-56fd-4947-a0e8-14e1d9b18224.JPG ☀ A Little Science Lesson: Why Does It Spin? This utilizes the principle of a "Solar Motor": When sunlight shines, the miniature solar cells absorb light energy and convert it into electrical energy, powering the windmill to rotate gently~ The stronger the sunlight, the faster it spins. It can even rotate slightly in dim, cloudy light, offering a soothing and low-energy experience. https://cdn-next.cybassets.com/s/files/5993/ckeditor/pictures/content_1f2fd202-27ae-474f-a611-91c5891dc7ae.gif ♦ The Principle of the Light Radiometer: Also known as the Crookes Radiometer, it was invented in 1875 by the British physicist and chemist Sir William Crookes (1832-1919). Inside the radiometer are four extremely lightweight mica vanes. One side of each vane is blackened. They are mounted on a fine pin to minimize resistance to rotation. The blackened side of the mica vanes inside the radiometer absorbs radiant heat, causing its temperature to rise. This increases the average kinetic energy of the gas molecules nearby, while the silver side reflects radiant energy, keeping its temperature constant and the average kinetic energy of nearby gas molecules unchanged. When gas molecules undergo perfectly elastic collisions with the surfaces, their change in momentum is twice the incident momentum. Therefore, the molecules rebounding from the black side experience a greater change in momentum than those from the white side. This results in a greater force on the black side, causing the vane to rotate clockwise. When it stops receiving radiant heat and gradually cools, the vane rotates in the opposite direction. (Content adapted from: Popular Science Education Website, Department of Physics, National Tsing Hua University) 🙋 Frequently Asked Questions (FAQ) Q: Does the windmill only spin in sunlight? Yes, this design relies on light for power. The brighter the natural light, the faster it spins; indoor yellow lighting is usually insufficient to activate it. Q: Can it be given as a birthday or good luck gift? Absolutely! Each design carries a unique meaning and comes with beautiful packaging, making it a wonderful choice for a gift that brings daily comfort or good fortune. Q: Will it break? Does it need batteries? It requires no batteries at all. The structure is simple, and it has a long lifespan. Please avoid dropping it or exposing it to prolonged, excessive sunlight (which can cause fading). Product Specifications: ► Dimensions: Height 12.5cm / Sphere Diameter 8cm ► Materials: Glass / Aluminum / Mica ► Origin: China Important Notes: ► Requires exposure to sunlight or heat-generating light bulbs (incandescent bulbs). ► To maintain extreme lightness, the mica vanes inside the light radiometer are blackened using a smoking process. During manufacturing, there may be a small amount of fine mica powder (from the black mica sheets) that detaches. Therefore, each piece may have slight adherence of mica powder inside the glass sphere, which is a normal phenomenon and not a defect. This notice is provided to prevent misunderstanding and future disputes. ► This is a glass product; please handle with care as it is fragile (all items are checked for cracks before shipping). ► This is a precision item; please do not shake it vigorously. ► Due to variations in shooting light and display monitors, there may be color differences between the actual product and the photos. The final color will be based on the actual item.