Coulomb's Law

Like charges repel, unlike charges attract.

The electric force
acting on a point charge

as a result of the presence of a second point charge
is given by Coulomb's Law:

where

= permittivity
of space

Note that this satisfies Newton's
third law because it implies that exactly the same magnitude of force
acts on .
Coulomb's law is a vector equation and includes the fact that the force
acts along the line joining the charges. Like charges repel and unlike
charges attract. Coulomb's law describes a force of infinite range which
obeys the inverse
square law, and is of the same form as the gravity
force.

For
=
x10^ C
=
x 10^ C
and r =
meters,
F= x
10^ Newtons.

A negative force implies an attractive force. The force is
directed along the line joining the two charges.

Electric
force example

More
on Coulomb's constant

Index

Electromagnetic
force

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Electricity and Magnetism

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Electric Force Example

The electric force between charges
may be calculated using Coulomb's
law.

Index

Electromagnetic
force

HyperPhysics*****
Electricity and Magnetism

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Coulomb's Constant

The constant of proportionality appearing in Coulomb's
law is often called Coulomb's constant. Note that it can be expressed
in terms of another constant,
= permittivity
of space.

When describing the electric forces in atoms and nuclei, it is often
convenient to work with the product of Coulomb's constant and the square
of the electron charge since that product appears in electric potential
energy and electric force expressions. That product in units appropriate
for atomic and nuclear processes is:

The electric force between charges
may be calculated using Coulomb's law.

Index

Electromagnetic
force

HyperPhysics*****
Electricity and Magnetism

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