Electric Fields

#### Electric fields in general

• For electricity, there are two charges: Positive and Negative.
• The charges follow the rule: Opposites attract, Like charges repel.
• We define the direction of an electric field as the direction a positively charged particle would take within a field.
• Using "Lines of Force," we can see how an electric field behaves.
• There are a few rules to apply in drawing and interpretation of these lines:
• Field lines begin on positive and end on negative.
• The angle they begin and end on is 90 degrees. (Must be indicated if drawn)
• Field lines never cross.
• Field lines that are closer together indicate a stronger field and vice versa.
• A negative particle would go the opposite direction to the field lines.

#### Point Charges

• A charged particle produces a radial electric field in the surrounding region.
• Similar to a gravitational field, any other charges within this field will experience a force.
• Also like a gravitational field, the strength of the field is inversely proportional to the distance away from the origin.
• Force on a charged particle can be given by
(1)
$$F = qE$$
• Where:
• $F$ is the force on the particle (N)
• $q$ is the charge on the particle (C)
• $E$ is the electric field strength ($Vm^{-1}$)
• The direction of force on a charge is as follows.
page revision: 2, last edited: 07 Jun 2011 08:24