This document discusses how to represent electric fields graphically using electric field lines. It explains that field lines indicate the direction of force on a positive test charge and that closer spacing of lines represents a stronger field. Examples are given of field line patterns for single isolated positive and negative charges, two charges of equal and unequal magnitude, and uniform fields between parallel plates and a point charge near a plate. Readers are instructed to download a worksheet to practice drawing field lines in different scenarios.

1. DRAWING ELECTRIC
FIELD LINES

2.  We have already discussed on the concept of Electric Field,
where it is a region of space where any charged particles in it
experiences a force.
 We can represent an electric field graphically using lines of
force known as electric field lines.
DRAWING ELECTRIC FIELD LINES

3. Field Line
 A field line indicates the
direction of the force a
positive charge would
experience if it is placed at
that point in the field.
 For example, an isolated
positive charge.
 The electric field lines due to
the isolated positive charge
would radiate outward
uniformly in all directions.
DRAWING ELECTRIC FIELD LINES
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4. Field Line
 A field line indicates the
direction of the force a
positive charge would
experience if it is placed at
that point in the field.
 For example, an isolated
negative charge.
 The electric field lines due to
the isolated negative would
radiate inward uniformly in
all directions.
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5.  The spacing between the lines indicate the strength of the
field.
 A stronger field would have more closely spaced lines.
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+
Stronger FieldWeaker Field

6.  Variations of field lines for 2 charges and for uniform fields
Unlike charges of equal magnitude
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Direction of field is
away from positive
charge
Direction of field is
into the negative
charge
The turning point (i.e. hump) of
the field lines is at the middle of
the two charges

7.  Variations of field lines for 2 charges and for uniform fields
Unlike charges (positive charge of larger magnitude)
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More field lines at
the charge with
larger magnitude
Less field lines at
the charge with
lower magnitude
The turning point (i.e. hump) of the field
lines is nearer the weaker charge

8.  Variations of field lines for 2 charges and for uniform fields
Like charges of equal magnitude
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For negative charges of equal magnitude, the shape
looks the same except for the direction of field lines.

9.  Variations of field lines for 2 charges and for uniform fields
Uniform electric field between two parallel metal
plates
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Field lines are parallel and equidistant to each other.
Field lines are perpendicular to the charged plates.

10.  Variations of field lines for 2 charges and for uniform fields
Point charge & Plate
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- - - - - - - - - - - - - - - - -
At the charged plates, field lines becomes
- parallel to each other, and
- perpendicular to the charged plates.

11.  Download the worksheet and attempt to draw the field lines
for the 4 different scenarios in the worksheet.
 You can use the applet found at ______ to help you visualise.
 Submit the worksheet to your tutor in the next tutorial lesson.
DRAWING ELECTRIC FIELD LINES