If the conductor is grasped with the right hand in such a way that the right thumb points in the direction of the current, the fingers wrap around the conductor in the direction of the magnetic field. The strength of a magnetic field around a conductor can be intensified by coiling the conductor into a loop. The magnetic field outside a solenoid resembles the field formed outside a bar magnet. Inside the solenoid the magnetic field consists of straight, uniformly spaced lines of flux. The magnetic field strength increases enormously if a material with a high magnetic permeability is used for the core of the solenoid.
Ferromagnetic materials have very high magnetic permeabilities.
State that the direction of the magnetic field around a current-carrying conductor depends on the direction of current flow through the conductor. Illustrate that the magnetic field around a current-carrying conductor forms a series of concentric circles. Recognize the effect that increased distance away from the conductor has on the strength of the magnetic field. Use the right-hand rule to determine the direction of the magnetic field lines or the direction of the current for a straight conductor. Explain that the strength of the magnetic field can be intensified by coiling the conductor into a loop.