Lever Lever A lever ( or ) is a simple machine consisting of a beam or rigid rod pivoted at a fixed hinge, or fulcrum. A lever is a rigid body capable of rotating on a point on itself. On the basis of the location of fulcrum, load and effort, the lever is divided into three types. It is one of the six simple machines identified by Renaissance scientists. A lever amplifies an input force to provide a greater output force, which is said to provide leverage. The ratio of the output force to the input force is the mechanical advantage
Mark A. Lever crust. Mark A. Lever Dr. Mark Lever (born 1977) is a microbial ecologist who studies the role of microorganisms in the global carbon cycle. He is a professor of environmental microbiology in the Department of Environmental Systems Science in the Institute of Biogeochemical and Pollutant Dynamics at ETH Zurich. Dr. Lever earned his MA in Marine Biology at the Boston University Marine Program at Woods Hole in 2002 and his PhD in Marine Sciences at the University of North Carolina, Chapel Hill in 2008. He worked as a postdoctoral scientist at Aarhus University from 2009 to 2014, when he joined