A lever is a simple machine that is used to lift or move heavy loads by use of relatively smaller forces. It uses a fixed support or hinge known as a fulcrum. A bar moves about this fulcrum. Effort is the work done on the lever and resistance is the load that needs to be lifted or moved. The distance between the fulcrum and the effort end is known as length of effort arm. The distance between the fulcrum and load or resistance end is known as the length of the resistance arm. The lever's capability is called mechanical advantage, which is defined as:
Mechanical advantage = length of effort arm / length of load arm
We want the mechanical advantage to be more than 1, so that lesser effort can result in the movement of a higher load.
It also follows from this equation that we prefer a greater length in the effort arm and a smaller length in the load arm. Thus, the fulcrum is ideally placed close to the load end and as far away as possible from the effort end.
Thus, if we move the fulcrum close to the effort end, the mechanical advantage decreases and we have to use more effort to move the same load.
Hope this helps.