Magnetic fields due to currents

The magnetic field lines are concentric circles around the wire, with the wire at the center. The direction of the field is determined by the right-hand grip rule: thumb in direction of current, fingers curl in direction of the magnetic field.

The magnetic field inside a long solenoid is approximately uniform and parallel to the axis of the solenoid. Outside the solenoid, the field is weak and resembles that of a bar magnet.

A ferrous core significantly increases the magnetic field strength of a solenoid. This is because the ferrous material is easily magnetized, aligning its magnetic domains with the solenoid's field and enhancing it.

Each conductor creates a magnetic field around it. The other conductor, carrying a current, experiences a force due to this magnetic field. Parallel currents attract, antiparallel currents repel.

The magnetic field lines pass through the center of the coil and form loops. The field is strongest at the center and weakens as you move away from the coil. It resembles the field of a short bar magnet.

Increasing the current directly increases the magnetic field strength inside the solenoid. The magnetic field strength is proportional to the current.