Matter & Energy


Matter is composed of atoms or groups of atoms called molecules. The arrangement of particles in a material depends on the physical state of the substance. In a solid, particles form a compact structure that resists flow. Particles in a liquid have more energy than those in a solid. They can flow past one another, but they remain close. Particles in a gas have the most energy. They move rapidly and are separated from one another by relatively large distances.

Field Direction and Strenght

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Field Direction

When a charge is placed at any given point in an electric field, it is acted on by a force that tends to push it in a certain direction. This direction is called the direction of the field at that point. The field direction can be represented graphically by the lines of force near an electric charge.

Field Strength

The strength, or intensity, of a field at any point is defined as the force exerted on a charge of 1 coulomb placed at that point. For example, if a point charge of 1 coulomb is subjected to a force of 10 newtons, the electric field is 10 newtons per coulomb at that point. An object with a charge of 5 coulombs would be subjected to a force of 50 newtons at the same point.

Field strength is represented graphically by the closeness (density) of the lines of force. Where the lines are close together, the field is strong. Where they are far apart, the field is weak. Near a charge, the field is strong and the lines are close together. At greater distances from the charge, the field weakens and the lines are not as close together. The field strength values that the lines represent are relative, since a field can be drawn with as many lines as desired.