Transcript Boardworks Static Electricity

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Michael Faraday’s lines of force
In the 1830s, the English scientist, Michael Faraday, observed
how iron filings arrange themselves around a bar magnet.
Faraday called the curved paths of the filings lines of force.
He visualized a similar
pattern of lines around
positive and negative
charges.
The lines of force
of an would start
on a positive
charge and end on
a negative charge.
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Are Faraday’s lines of force real?
Faraday believed that lines of force were physically
everywhere in space; this was not correct.
However these lines
of force are useful for
visualizing the region
of space where the
forces of electric
charges are felt.
This region of
space is called
the electric field.
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Charges and electric fields
All charged objects are surrounded by a region called an
electric field.
An electric field is a region where a
charged particle will experience a force.
Electric fields can be represented by electric field lines.
● The direction of the lines represents the direction of the
field – it shows the direction a positive charge would move
in the field.
● The distance between lines represents the strength of
the field – the closer the lines, the stronger the field.
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Drawing electric fields
The field consists of a family of lines extending evenly in all
directions to or from the charge.
The rules of drawing electric fields are:
1. The lines start on positive
charges and finish on
negative charges.
2. The number of lines drawn is
proportional to the strength of
the charge.
3. No two field lines ever cross.
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The shape of an electric field
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How big is the electric field?
The electric field extends to infinity – this means that it
goes on forever.
You can draw the field lines as long as
you want. But remember that the longer
the field lines are, the further the ends of
the lines are from each other.
What does this mean about the
strength of the electric field as
you get further away?
As the distance from the electric
field increases, the strength of the
electric field decreases.
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Effect of distance and charge on force
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