# Electromagnetic Force

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Electromagnetic force is one of the four fundamental forces in nature. The electromagnetic force manifests itself through the forces between charges (Coulomb's Law) and the magnetic force , both of which are summarized by the Lorentz Force Law.

Fundamentally, both magnetic and electric forces are manifestations of an exchange force involving the exchange of photons . The quantum approach to the electromagnetic force is called quantum electrodynamics or QED. The electromagnetic force is a force of infinite range which obeys the inverse square law, and is of the same form as the gravity force.[refer]

The electromagnetic force holds atoms and molecules together. In fact, the forces of electric attraction and repulsion of electric charges are so dominant over the other three fundamental forces that they can be considered to be negligible as determiners of atomic and molecular structure. Even magnetic effects are usually apparent only at high resolutions, and as small corrections.[refer]

## Coulomb's Law

If two particles having charges q1 and q2 are at rest with respect to the observer, the force between them has a magnitude

$F = \frac{1}{ 4 \pi \varepsilon _ 0 } \frac{ q_1 q_2}{r^2}$

where ϵ = 8.85419 × 10-12 C2N-1m2 is a constant. The quantity $\frac{1}{ 4 \pi \varepsilon_0}$ is 9.0 × 109 Nm2C-2. This is called Coulomb force and it acts along the line joining the particles.