3D Magnetic Field of a Current – Straight Wire, Circular Loop and Solenoid

PhysicsElectric & Magnetic FieldsAges 17–18

A rotatable 3D model of the magnetic field lines around a long straight wire (concentric circles, right-hand grip rule), a circular loop and a solenoid. Adjust the current I, reverse its direction and drag a probe to change the distance r; small compass needles on the plane turn to follow B, and the magnetic flux density B = 2·10⁻⁷ I/r (straight wire), 2π·10⁻⁷ I/R (centre of the loop) or 4π·10⁻⁷ nI (inside the solenoid) updates continuously.