The Lens Equation An image formed by a convex lens is described by the lens equation 1 u 1 v 1 f where uis the distance of the object from the lens. Focal Length Formula Finding focal length uses the focal length formula and requires knowing the distance from the original object to the lens u and the distance from the lens to the image v. It may be written as.
A form using the Cartesian sign convention is often used in more advanced texts because of advantages with multiple-lens systems and more complex optical instruments.
The formula is as follows. Frac1ufrac1vfrac1f The lens formula may be applied to convex lenses as well as concave lenses provided the real is positive sign convention is followed. It is the formula or we can say the equation that relates the focal length the distance of the object and the distance of the image for a lens. A lens is a transmissive optical device that focuses or disperses a light beam by means of refractionA simple lens consists of a single piece of transparent material while a compound lens consists of several simple lenses elements usually arranged along a common axisLenses are made from materials such as glass or plastic and are ground and polished or molded to a desired shape.