A new group of forces – without contact(Exposition)

Some new forces

Now look at a group of forces — magnetic, electric and gravitational — which are different in kind from the direct contact pushes and pulls met so far.

These three forces allow remote part of the environment to exert a force on an object without being in contact with it. Thus, a magnet attracts or repels another magnet; a rubbed (or electrically charged) rubber balloon attracts bits of paper; the Earth attracts masses. Each of these is an action at a distance or non-contact force.

These days the concept of gravity is relatively common-place. If you ask people why things fall, more often than not they will tell you that it is because of the pull of gravity. Despite this familiarity, we should not lose sight of the fact that this is a very strange idea indeed and has been the subject of puzzlement throughout the history of science.

For example, if you drop a melon from the top of a building, how can the Earth (whose surface is some 10 metre away) exert a force on that melon?

What we do know is that such action at a distance forces are very real and we experience them every day. All three non-contact forces decrease in strength as separation between objects increases. Here we give only a brief introduction to each force.