Free Magnetic Field Calculator
Calculate the magnetic field around a long straight current-carrying wire using B = mu0 * I / (2 * pi * r).
A
m
Magnetic Field
0.00004000 T
Magnetic Field (μT)40.00 μT
Magnetic Field vs Current
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.
Example Calculation
Magnetic field 5 cm from a wire carrying 10 A.
- 01B = mu_0 * I / (2*pi*r)
- 02B = 4*pi*1e-7 * 10 / (2*pi*0.05)
- 03B = 4e-6 / 0.1
- 04B = 4e-5 T = 40 μT
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