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Electric Field
Jun 10, 2025
Introduction to electric field and how to calculate electric field using Coulomb's law
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0:00
in the previous tutorial we talked about
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electrostatic force coolum's law and the
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principle of superposition and in this
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tutorial we talk about electrostatic
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field electrical interactions between
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charged particles can be reformulated
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using the concept of electric field to
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understand the concept of electric field
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consider that we have two positively
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charged bodies namely A and B and we
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also know that these two positively
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charged bodies will reppel each other
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with a force
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[Music]
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F if we now remove this charge
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B from its position and label its
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position as
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Point p
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then this charged body a is set to
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produce an electric field at this point
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P now this charge a not only produces
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field at this point P but it also
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produces field at all other points in
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its
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vinity so if we place a Charged body B
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either positive or negative at this
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point p a force is exerted on this body
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B by the field produced by body a and
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since electric field exists at all point
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in the region around a this charged body
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B will experience a force at any point
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in the space around body
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a suppose we have to test the presence
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of electric field at a point say p in
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the region around this charged body a
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now to do this we simply place a small
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charg body at this point
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p and if this test charge experiences
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any force of electric origin then
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electric field e is set to exist at this
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point P so we can now say that an
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electric field is set to exist at a
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point if an electric force is exerted on
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a t charge at that point now electric
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field
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like electric
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[Music]
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force is also a vector
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quantity so the properties of electric
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field are determined when both magnitude
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and direction of an electric force are
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specified now
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if f is the force acting on test
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charge Q D placed at a point in an
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electric field then electric field at
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that point would be equal
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to e =
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to F upon Q
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D and
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[Music]
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since f is equal to
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q- e direction of electric field would
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be same as the direction of electric
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force
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now SI unit of electric field is Newton
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per
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Kum so we now know about electric field
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but we do not know how to calculate this
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electric field the electric field at any
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point can be calculated using kum's law
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if we know about both magnitude and
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position of all the charges contributing
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to the
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field now to find the magnitude of
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electric field at a point P at a
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distance R from the charge Q imagine a
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charge q- placed at this point p and
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from kum's law we
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have Force f is equal to K
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q q d upon r² where we know that this
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proportionality constant K is = 1 upon 4
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Pi
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Epsilon and electric field at this point
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p is given
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[Music]
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by e = f upon
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Q D is = to 1
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upon 4 Pi
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Epson Q upon r² now direction of this
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electric field e is away from the charge
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Q if it is positive and it would be
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towards the charge Q if the charge is
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negative now electric field in terms of
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unit
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Vector R cap directed along the line
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from charge Q to point P would
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be a = to
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k q r
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cap upon
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r² where R is the distance from charge Q
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to point p and this equation holds for
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both positive and negative
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charges
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now if there are n number of charges
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present in a system say
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q1 Q2 Etc which are at a distance
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R1 R2 Etc from a given point
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P then each one of the charges exert a
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force on test charge q- placed at this
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point P now from principle of
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superposition net force on the test
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charge q- would
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[Music]
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be F = to
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fub1 plus
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[Music]
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FS2 and so on where this fub1 is forc on
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test charge due to charge q1 and so on
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and the resultant electric field would
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also be the vector sum of the individual
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electric fields
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[Music]
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[Applause]
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so resultant electric field E equals
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to F upon
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q- is equal to
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E1
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plus
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E2 and so on this is also a direct
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result from the principle of
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superposition similar to what we have
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discussed while studying electric force
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on a single charge due to a system of
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multiple
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charges and for more information visit
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physics catalyst.com
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[Music]
#Physics
#Primary & Secondary Schooling (K-12)