Download Chapter 21 Notes

Chapter 21 Notes
Electric Fields
Electric fields – these relate the force (N) exerted on a charge (C) to its size
In other words, the larger the charge…
If the size of the charge is doubled, so is the force.
Formula:
Electric Field =
____F_____
q’
F = force in Newtons
q’ = test charge in Coulombs (C)
Electric Field units are N/C
(Newton/Coulombs)
*the direction of the electric field will be the direction of the force on the
positive charge
*Electric Field lines – see page 485 figure 21-2
 The distance between the lines will indicate the strength of the
field – the closer the lines the stronger the field
 Lines always leave the positive and enter the negative
Example problems:
1. A negative charge of 2.0 X 10-8C experiences a force of 0.06N to
the right in an electric field. What are the field magnitude and
direction?
2. A positive test charge of 5.0 x 10-4C is in an electric field that
exerts a force of 2.5 x 10-4 N. What is the magnitude of the electric
field at the location of the test charge?