Psychokinesis is the term given to moving objects with mind energy which contains electro magnetic energy, it's also known as PK. In its strongest form it is often associated with poltergeist activity although Poltergeist is a German word meaning "noisy ghost", its definition shouldn't really be attributed to PK because the word doesn't mean that. It was commonly associated with adolescent teenage girls. It can range from raps and taps to moving furniture.
There is no real difference between Psychokinesis and Telekinesis a lot of people think they are different, they are two different words to describe the same thing just like OBES and Astral Projection, OBES being spontaneous and Astral projection is consciously doing it. Psychokinesis is mind over matter, psycho=mind and kinesis=movement, as with an OBE Psychokinesis can sometimes be spontaneous. Telekinesis is movement of objects by thought, like Astral Projection this is a conscious effort to move something, but in both cases they both use the same energy so there is no difference really.
Energy is always there, and always will be, but like with any energy it can be stimulated for example passing an electric current over a magnet will cause movement like in a motor, thus one energy force (electricity) cause another energy force (movement) stimulating the energy, in fact you can apply this theory to things to do with spirit, magnetism, electricity and movement, any 2 of these together will cause the third, movement and magnetism will cause electricity, like with a dynamo, this is one known way how spirit move objects, sometimes when their energy comes into contact with electricity it will cause movement, this is probably why spirit like electrical items so much as they can use the energy to their advantage.