## Can electricity (static or not) be used to move very large objects? Could you somehow control a sufficiently strong electrical current through the air or across a surface to lift a log or a car? Are there certain objects it could lift and certain ones it couldn't?

Static electricity works because objects which are otherwise "neutral" (in other words, objects with no net charge) can be polarized. An electric field, like one caused by a nearby charged object, can cause the charges inside of a neutral object — the protons and electrons — to move around a tiny bit.

Inside the bulk of the neutral object, this has no effect. On the outside surface, however, a small amount of positive charge accumulates on one side and a small amount of negative charge builds up on the other. You haven't added or removed any charge, just caused it to separate a little. This separation causes the polarized object to be attracted to charged objects.

For example, a charged balloon placed near a neutral pith ball will cause the pith ball to become polarized and be attracted to the balloon.

In the image above, the balloon collected negative charges from the sweater. When placed near the right wall, the negative charges repel, polarizing the wall and attracting the balloon. Click the image for an interactive simulation about polarization. Image Credit: PhET/CU-Boulder

Because polarization can only move the charges that already exist, the effect has very little strength. You wouldn't be able to get enough charge to the surface of a heavy object in order to lift it. You can try this at home: Charge a balloon by rubbing it on the carpet or your head, and see how big of a neutral object you can pick up.

If you had a way to electrically charge the object you wanted to lift, you could increase the force (because you'd have more charge). A Coulomb Balance works in this way. But you'd quickly reach a physical limit when moving heavier objects this way: the breakdown field of air.

Because we need so much charge to move something heavy, we create very large electric fields (more charge = stronger electric field). When you get to an electric field strength of about 3 million volts per meter, air ionizes - so the charge arcs across the ionized air and discharges the objects (this is precisely what lightning is: electrical arcing between the clouds and the ground!). So you can't go above that field strength, which would limit you quite a bit.

If you have a couple of wires, you can send current (moving electrical charges) through them, causing them to attract or repel. But this only works for two wires; it wouldn't work for normal objects like trees or cars, for instance.

The last "electrical" lifting mechanism involves electromagnets. Moving electric charges create a magnetic field, so if you wanted to lift a car or something else that is susceptible to magnetism, you could use a giant electromagnet (just like you see in the junkyard). That method, in the end, is limited by the magnetic susceptibility of the material. Things made of iron would be easily lifted, but things made of wood or cloth would not.

As you can see, we can use electricity to lift different objects, but we have to be clever in how we apply that electricity!