Transcript 02.Electric Fields

Ch. 21
Electric Fields
An electric field develops around
charges and between charges.
The Strength of an electric field
depends on the size of the charge and
the distance away from the charge.
The direction of the field is the
direction the force exerts on a positive
charge.
The Strength of an Electric Field:
E = F/q
E=electric field strength
F= force on a charge
q= charge
Substituting Coulomb’s Law we get:
E= kq/d2
Since k is a constant we get:
E=q/d2
The force on a charge in an electric field is a vector –
meaning it has magnitude and direction.
So … Electric field lines tell us the direction and force
of the e-field.
3/4
LT#1: Draw electric field lines for multiple charges
LT#2: Calculate the strength of an electric field
E-Field practice
“Charge and Fields” and “Electric Field Hockey” simulations
(Lab B)
Electrical charges flow like a ball rolling down a hill.
Without a change in elevation, the ball won’t roll.
Without a change in voltage, a charge won’t flow.
Lines that connect points of the same
voltage are called equipotential Lines
(similar to contour lines)
If lines are closer together the voltage (or
elevation) difference is greater.
Electric field lines run perpendicular to
these equipotentional lines