Page 76 - Physics 10_Float

ELECTROSTATICS

as electric lines of force. These lines were introduced by Physics Insight
Michael Faraday. The field lines are imaginary lines around a
field charge with an arrow head indicating the direction of
force. Field lines are always directed from positive charge
towards negative charge. The spacing between the field lines
shows the strength of electric field.

Electric field lines for an isolated Electric field lines for an isolated
positive point charge. negative point charge.
Variation of magnitude of
Coulomb’s force between two

13.6 ELECTROSTATIC POTENTIAL opposite charges of different
magnitudes.
The gravitational potential at a point in the gravitational field Quick Quiz
is the gravitational potential energy of a unit mass placed at
that point. Similarly, the electric potential at any point in the
electric field is the electric potential energy of a unit positive
charge placed at that point.

Electric Potential : Electric potential at a point in an electric
field is equal to the amount of work done in bringing a unit
positive charge from infinity to that point.
If W is the work done in moving a positive charge q from If we double the distance
infinity to a certain point in the field, the electric potential V between two charges, what
W
at this point would be given by V = will be the change in the force
q between the charges?
.......... (13.6)

It implies that electric potential is measured relative to some Physics insight
reference point and like potential energy we can measure The electrostatic force acting on
only the change in potential between two points. two charges each of 1 C separated
9
by 1 m is about 9 × 10 N. This force
Electric potential is a scalar quantity. Its SI unit is volt which is is equal to the gravitational force
-1
equal to J C . that the Earth exerts on a billion
If one joule of work is done against the electric field in bringing kilogram object at sea level!
one coulomb positive charge from infinity to a point in the

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