Bi-convex Lens 50mm FL 500mm

This optical glass lens set demonstrates refraction of light. This double convex (also called bi-convex) lens has a focal length of 50cm and measures 5cm in diameter. The bi-convex lens is made of optically worked glass, with ground edges, highly polished. Convex lenses are used for a variety of things, but probably the most known one is in glasses and contacts to help correct vision. Convex lenses are bent outwards – in other words, the centre of the lens is thicker than the edges. When light reaches the lens in a straight line, the lens will bend the light rays to a specific focal point. This focal point is lens-dependent and is different for the lenses included in the set. Convex lenses are also called positive lenses, they converge the light rays towards one point. A great classroom activity with convex lenses is to make your own telescope. Use one convex lens with a diameter of 5cm and a focal length of 50cm, and one concave OR convex lens (a convex lens will flip the image) with a diameter of 5cm and a focal length of 15cm. You will also need a paper towel roll, some flexible cardboard paper and tape. Roll the cardboard the long way to form a tube, it will have to be the same diameter as the lens. This tube will be the eyepiece. The lens used for the eye piece is the lens with the shortest focal length. Tape the edges of this lens to the tube. Tape the other lens (with the longer focal length) to the end to the paper towel roll. Once this is done, insert the empty end of the cardboard tube into the paper towel roll. And that’s all! You can now look through the eyepiece lens and slide the cardboard tube in and out the paper towel tube until the object you’re looking at is in focus.