Enter your solenoid's Number of Turns (N), Length (L), Current (I), and Material Type (or a custom Relative Permeability (μr)), and the Solenoid Magnetic Field Calculator gives you the resulting Magnetic Field (B) along with your coil's Turns per Meter density.
Magnetic Field (B)
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Magnetic Field
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Turns per Meter
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A solenoid is a wire wound tightly in a long, thin coil. When electric current flows through it, it creates a strong magnetic field inside and little magnetic field outside. Solenoids are used in many practical applications to create controllable magnetic fields.
The magnetic field inside a long solenoid is calculated using the formula B = μNI/L, where B is the magnetic field, μ is the permeability, N is the number of turns, I is the current, and L is the length of the solenoid.
For an ideal infinite solenoid, the magnetic field outside is zero. For real finite solenoids, the external field is very weak compared to the internal field, especially near the center of a long solenoid.
The magnetic field in a solenoid originates from the electric current flowing through the wire. Each turn of wire creates a small magnetic field, and when many turns are wound together, these fields add up to create a strong uniform field inside.
The magnetic field strength is directly proportional to the number of turns. Doubling the number of turns doubles the magnetic field, assuming the length and current remain constant.
The permeability of free space (vacuum permeability) μ₀ = 1.25664 × 10⁻⁶ T·m/A. This constant appears in the solenoid magnetic field equation and represents the ability of vacuum to support magnetic fields.
The core material affects the magnetic field through its relative permeability (μr). Air has μr = 1, while ferromagnetic materials can have μr values of hundreds or thousands, greatly amplifying the magnetic field.
Magnetic field is measured in Tesla (T) in the SI system. Other common units include Gauss (G), where 1 T = 10,000 G. Current is in Amperes (A) and length in meters (m).