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Electric Field Strength
A gravity field is where a force is exerted on a mass; an electric field is a region
where a force is exerted on a charge.
The electric field strengthis defined as force per unit charge. In equation form
this is represented as:
E = F/Q
[E electric field strength; F force; Q charge]
E is a vector quantity and its units are newtons per coulomb, N/C. It can be
negative (attractive) or positive (repulsive).
Since the electric field strength is defined as force per unit charge, we can write:
This equation is true for all point charges, which can be considered to have a
radial field. A spherical charge can also be considered to have a radial field
provided the distance from the charge to the centre is much greater than the
radius of the sphere.
We can plot a graph of electric field strength against distance:
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We can see that the graph shows a classic inverse square law.
Where two charged plates are close together, the radial fields of the charges
combine to make a uniform field .
Notice that the field bulges at the ends; generally we ignore this.…read more