Electric Fields – Learn

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An electric field is a region of space around a charged object in which another charged object will experience a force. An electric field is a vector quantity because it has both a magnitude and a direction. The force that a charged object will experience is either attractive or repulsive, depending on the charges of the two objects. Like charges repel (positive-positive or negative-negative), unlike charges attract (positive-negative)        

Electric fields are represented by field lines. The field lines are a useful way of visualising the strength and direction of the field. When drawing electric field lines around a charged object (in two dimensions), the following points apply:

• The field lines point in the direction of the force that a positive charge within the field would experience
• Electric field lines begin on positive charges and end on negative charges
• A positive charge experiences a force in the direction of the electric field, and a negative charge experiences a force in the opposite direction to the field
• The spacing between the field lines indicates the strength of the field. The closer together the lines are, the stronger the field
• Around point charges, which can be thought of as small charged spheres with no spatial extent, the electric field radiates in all directions (three dimensions)
• Between two oppositely charged parallel plates, the field lines are parallel and therefore the field has a uniform strength
• When charged particles are in an electric field, they accelerate in the direction of the force acting on them

Below are some common field diagrams:

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Point Charges

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Pairs of Charges

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Dipoles

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Parallel Charged Plates

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