ELECTRIC FIELD

ELECTRIC FIELD 

Electric field, E, at a point can be defined as the electric force experienced by a test charge q at the point

Electric field can be defined as electric force per unit charge

A POINT OF CHARGE

The electric force on a charged body is exerted by the electric field, created by other charged body.

The charged body A produces or causes an electric field at point P. This electric field is present at P even if there is no charge at P; it is a consequence of the charge on body A only. Then a point charge q’ is placed at point P, it experiences the force F’. We can say that this force is exerted on q’ by the field at P

(Negative sign denotes that the direction of the electric field E is in the opposite direction of increasing r)

A charge particle moving through an electric field caused the electric potential energy changes.

• Two charges with opposite (Attract)

o   Potential energy (product of q1q2) should negative

• Two charges have same sign (Repel)

o   Potential energy (product of q1q2) should be positive

o   Electric force is repulsive

o   Potential energy increases as they move closer

Figure 1: Two different charge

ELECTRIC FIELD LINES

Electric field lines are an imaginary line or curve drawn through a region of space so that its tangent at any point is in the direction of the electric-field vector at that point (field lines are never intersecting)

Electric field lines show the direction of E at each point. The line spacing gives the magnitude of E at each point. When E is strong, the lines a drawn closely together while it far apart when it is weaker.

• Single positive charge – the line always points away from the charges and towards negatives charge
• Each point for opposite charge in space – the electric field vector is tangent to the field line passing through that line
• Each point for same charge in space – the lines are closer together where the field is strong, farther apart where it is weaker

Figure 2: Repulsion field lines (same charge)

Figure 3: Attraction field lines (opposite charge)

Figure 4: Single charge field lines (positive and negative)