Have you heard of the Moser lamp? It is a light bulb (灯泡) that uses no electricity. It was invented by Alfredo Moser, a Brazilian engineer, and it brings light to homes and small businesses in some very poor countries.
The Moser lamp is made of a plastic bottle filled with water and a little bleach (漂白剂) . It is fixed into a round hole in the top of a building, so that the upper part appears in the sun and the lower part hangs down into the room. The sunshine falls on the upper part of the bottle and makes the water produce light, so the bottom of the bottle shines like an electric bulb.
Clearly, there's a weak point: It doesn't work at night. But in some very poor and crowded areas, houses often have small windows or none at all. Even during the day, the room is dark. The Moser lamp is widely used in these areas.
This idea came up because of a power cut. That day, Moser and his friends talked about how to live without electricity. They imagined if they were lost in the wild, how could they give the alarm? One suggested using a lens (透镜) to focus the sunshine and start a fire. If they didn't have a lens, they could find a plastic bottle with water. This would act as a lens. This idea came into Moser's head. Almost by accident, he developed the lamp.
Now Moser's lamp is used in around 15 poor countries. It has changed the lives of a large number of people.
