On a Bright Day:
A great deal of energy falls on the Earth’s surface – roughly 1 kW per square meter. This is about 0.6 Watt per square inch. This doesn’t sound like much energy, but suppose we collect and concentrate 63 square inches of this sunlight? These 63 square inches would collect about 38 Watts of energy. This doesn’t sound like much, but…
Suppose We Could Then:
Concentrate these 38 Watts into an area of only 1/8 of a square inch? This is exactly what we can do with an inexpensive plastic Fresnel lens. We’ll focus the sunlight into an area 3/8” in diameter – this is the equivalent of 300 Watts per square inch! With this energy level, we can easily ignite a piece of wood, boil some water, and even melt a penny.