Magnetic Field Calculator Formula

Understand the math behind the magnetic field calculator. Each variable explained with a worked example.

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Formulas Used

Magnetic Field

magnetic_field = 4e-7 * pi * current / (2 * pi * distance)

Magnetic Field (μT)

magnetic_field_ut = 4e-7 * pi * current / (2 * pi * distance) * 1e6

Variables

VariableDescriptionDefault
currentCurrent(A)10
distanceDistance from Wire(m)0.05

How It Works

Magnetic Field of a Straight Wire

A current-carrying wire generates a circular magnetic field around it.

Formula

B = mu_0 * I / (2 * pi * r)

where mu_0 = 4*pi x 10^-7 T·m/A is the permeability of free space. The field direction follows the right-hand rule.

Worked Example

Magnetic field 5 cm from a wire carrying 10 A.

current = 10distance = 0.05
  1. 01B = mu_0 * I / (2*pi*r)
  2. 02B = 4*pi*1e-7 * 10 / (2*pi*0.05)
  3. 03B = 4e-6 / 0.1
  4. 04B = 4e-5 T = 40 μT

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