LS3.0 Fresnel Lense - Lunchbox Science Note Cards

The Back of the Card says:

Fresnel Lense

The Fresnel lens was Invented for the Lighthouse. How is it used today?

Split Rock Lighthouse was built in Minnesota on Lake Superior after a 1905 storm lost 29 ships. A midsize glass Fresnel lens approx. 5.2 ft in height (originally developed by French Physicist in 1822) was installed. Becky's painting shows an enlarged cross-section of the lens. The stair step design refracts and reflects the light to focus the beam for 22 miles. This design allows a much smaller and lighter lens than would otherwise be needed if it was standard convex.

Today, plastic Fresnel lenses are even lighter and used as a book page magnifier, or to concentrate heat in a solar oven, a solar water heater and even a solar powered steam engine.

Each card comes as individual or set of 6 of same or variety pack of Eight 4 by 6 Note Cards with envelopes.