The SI unit of electric charge is the coulomb (C), which is defined as the amount of charge that flows through a conductor in one second when a current of one ampere flows through it.

The electric field is the gradient of the electric potential, which means that the electric field points in the direction of the greatest rate of change of the electric potential.

The Lorentz force is the force exerted on a moving charge in a magnetic field. It is given by the equation (F = q(E + v x B)), where (q) is the charge of the particle, (E) is the electric field, (v) is the velocity of the particle, and (B) is the magnetic field.

In an electromagnetic wave, the electric and magnetic fields are perpendicular to each other and to the direction of propagation of the wave.

The speed of an electromagnetic wave in a vacuum is approximately 3 x 10^8 m/s, which is the speed of light.

The electromagnetic spectrum is the range of all possible frequencies of electromagnetic radiation, from the lowest frequencies (such as radio waves) to the highest frequencies (such as gamma rays).

The principle of electromagnetic induction states that a changing magnetic field induces an electric field. This is the principle behind the operation of generators and transformers.

The SI unit of magnetic flux density is the tesla (T), which is defined as one weber per square meter.

Magnetic flux density is the gradient of magnetic field strength, which means that the magnetic flux density points in the direction of the greatest rate of change of the magnetic field strength.

The force between two parallel wires carrying current in the same direction is attractive. This is because the magnetic fields created by the currents in the wires are in the same direction, which causes the wires to attract each other.

The force between two parallel wires carrying current in opposite directions is repulsive. This is because the magnetic fields created by the currents in the wires are in opposite directions, which causes the wires to repel each other.

The magnetic field strength around a long, straight wire is directly proportional to the current in the wire. This is because the magnetic field is created by the moving charges in the wire, and the more charges that are moving, the stronger the magnetic field.

The magnetic field around a long, straight wire is circular. This is because the magnetic field lines are always perpendicular to the direction of the current in the wire.

The direction of the magnetic field around a long, straight wire depends on the direction of the current in the wire. If the current is flowing in the positive direction (from left to right), the magnetic field lines will be in a counterclockwise direction. If the current is flowing in the negative direction (from right to left), the magnetic field lines will be in a clockwise direction.

The SI unit of inductance is the henry (H), which is defined as the inductance of a circuit in which an electromotive force of one volt is induced by a current of one ampere.