Forces and "work". I've read that no matter what force is acting upon an object, no actual "work" is being done unless the object moves. This seems easy to accept if one is thinking about a bookshelf keeping a book from falling (the shelf is propping the book up and keeping it from falling, and the falling that would occur if the shelf disappeared is called "potential energy". What I have a problem with is this concept as it applies to forces "at work". Say we have a steel bar tied to one end of a string, with the other end of the string fastened to the floor. We then attach an electromagnet to the ceiling, and feed it with just enough current that the steel bar is suspended in the air, completely immobile, several inches below the electromagnet, with the string (pulled tight) preventing it from reaching said electromagnet. There is an air-gap between the steel bar and the electromagnet (this gap isn't actually necessary for the purposes of my question, but just makes it easier to visualize the issue, at least for me). Ok, so we can measure the electrical current being constantly fed into the electromagnet, and if we lessen the current by any amount, the steel bar falls to the ground. This implies to me that the current flowing through the coil of the electromagnet must be "working" to keep the steel bar suspended in mid-air below the electromagnet. If we lower (or completely eliminate) the current flowing through the coil, it no longer "works" to keep the steel bar where it is and the bar falls. So am I confused over simple semantics where "work" is concerned? When a force is the only thing keeping an object from moving (ie. electromagnet prevents bar from succumbing to another force (gravity) and falling due to the electricity being constantly fed into the electromagnet), and the removal of said force instantly allows the object to move, how can the force (or the electricity which creates the force) be thought of as not doing any work? Does my hydro bill not prove that work has been done?