Our world is made up not only of many visible objects, like lightning and magnets, but also many invisible objects, forces, and ‘fields’.

• Here, ‘field’ is not referring to a large grassy area, or to a part of a farm, but to something that fills all of space around us.
• Two of the most familiar of these invisible fields are the electric field and the magnetic field (which together are called the electromagnetic field); they provide the potential energy that causes electromagnetic forces.

Particles possess a number of properties that identify them, including their mass and charge.

• The charge of a particle determines how strongly the electric and magnetic fields will push or pull on the particle, and the mass affects how quickly the particle will change its speed and direction.

As we know from Newton’s second law of motion, force is equal to the product of mass and acceleration (F=m*a).

• If an object is accelerated by changing its velocity (either its speed or direction of motion), then there must be some force acting on it.
• When we use a magnet, the force involved is the electromagnetic force.