Why moving charge produce magnetic field?

A moving charge produces a magnetic field due to fundamental principles of electromagnetism. Here's the explanation:

The basic principle: - Stationary charges produce only electric fields - Moving charges produce both electric fields AND magnetic fields

Why this happens: According to special relativity, when a charge moves: 1. The electric field lines become compressed in the direction perpendicular to motion 2. This field distortion manifests as what we observe as a magnetic field 3. Essentially, magnetism is relativity's correction to electricity for moving charges

Mathematical description: - The magnetic field B around a moving charge is given by the Biot-Savart law - B = (μ₀/4π) * (q v × r̂)/r² - Where: - μ₀ = permeability of free space - q = charge - v = velocity vector - r = distance from charge

Practical implications: - Electric currents (moving charges in wires) create magnetic fields - This is how electromagnets work - Permanent magnets have moving charges at atomic level (electron spin and orbit)

The unified view: Einstein's theory of relativity shows that electric and magnetic fields are actually different manifestations of the same fundamental force - the electromagnetic force. What appears as purely electric in one reference frame appears as a mixture of electric and magnetic in another frame.

This connection between moving charges and magnetic fields is the foundation for most electrical technology, from generators and motors to transformers and speakers!