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Biot–Savart Law

Gives the magnetic field produced at a point by a small element of current-carrying wire.

Formula

dB=μ04πI dlsin⁡θr2dB = \frac{\mu_0}{4\pi} \frac{I \, dl \sin\theta}{r^2}

Variables

dBMagnetic field contribution
\mu_0Permeability of free space
ICurrent
dlLength element
rDistance to the point

Example

Integrating around a loop gives the field at the centre of an electromagnet.

Did You Know?

Discovered in 1820, just weeks after Ørsted first noticed a current deflecting a compass needle.

magnetismbiot-savartcurrentelectromagnetismlaw

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