Electric Fields

Electric Field

Electric fields are said to exist in the areanear CHARGED objects.

A charged object in an electric fieldexperiences ELECTROSTATIC FORCE

The amount of force depends on:-Strength of the field (E)-Charge on the object (q)

F = Eq

Example• An object with a charge of -2 coulombs

positioned in a uniform electric field experiences a force of -300 newtons. What is the strength of the electric field?

E= F/q

E = -300 N / -2 C

E = 150 N/C

Unit for electric fieldstrength is

Newton per Coulomb

Example• What is the force experienced by a 0.05

coulomb charge when it is placed in an electric field with a strength of 3 x 103 newtons per coulomb?

F = Eq

E = (3 x 103 N/C)(0.03 C)

E = 90 N

Electric Field Maps

Electric field lines can be mapped using aPOSITIVE test charge

1. Place the test charge near the object

2. Decide which direction the charge will move

3. Draw a field vector in the direction of motion

Area around a POSITIVE charge

+ +

- +

Area around a NEGATIVE charge

Field lines point:OUTWARD from +INWARD toward -

Electric Field Mapping

+ -

Field lines NEVER CROSS

+

Electric Field Mapping

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