ELECTRIC FIELDS
What Are Electric Fields?
 An electric field is the area around a charge
(either positive or negative) that is used to
show electrical forces generated by that
charge
 Electric fields are shown as arrows originating
with the charge
 The direction of the arrow is given by what a
positive test charge would do if dropped
within the electric field of the charge
Pictures of Electric Fields
How To Calculate Electric
Field Strength
 Electric field strength (E) can be calculated
with the equation:
 E = F/q
 E: Electric Field (N/C)
 F: Force felt by the charge (from
Coulomb’s Law)
 q: Charge of the object
Magnetism and Electric
Fields
 Electricity and Magnetism are extremely
closely related. So much so that they often
follow the same equations.
 Magnetic field lines follow the same pattern
as electric fields
 Before we get into “B Fields”, we need to first
understand the magnet…
The Simple Bar Magnet
 All magnets are made of two halves, or “poles”:
north and south
 North and south attract each other, just like positive
and negative particles!
 A north and a south can never be separated: if you
break a magnet in half you will always have a north
and a south, all the way down to a microscopic level!
How Do Magnetic Field Lines
Look?
 Magnetic Field lines, called “B Field lines, look
identical to electric field lines.
 The north pole of the magnet acts as a
positive charge, and the south acts as a
negative
What Happens When We Put
Magnets Together?
Earth and Magnets
 The earth has its own magnetic field,
generated by its rotation.
 The North Pole (geographic north) of the
earth acts as a south pole magnet (magnetic
south), and the South Pole (geographic south)
of the earth acts as a north pole magnet
(magnetic north).
 This explains why the north needle on a
compass is attracted to the North Pole!
Video
 Electric Field Video
 Electric Field Problem Walkthrough Video
Simulations
 Electric Field Hockey
 B Field Simulator
Picture Credits
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Slide 3: downloadanswer.com
Slide 4: facstaff.gpc.edu
Slide 4: mcat-review.org
Slide 7: newsouthwales.inetgiant.com.au
Slide 7:scienceblogs.com
Slide 8: facstaff.gpc.edu
Slide 9: ehow.com
Slide 9: sciencephoto.com
Slide 11: tigon2008.multiply.com