Magnetism produces lines of force known as flux. These can be detected by the compass needle showing the direction you are traveling as the earth's magnetic north pole attracts the north ends of other magnets. Magnetic lines of force start from the north pole and end at the south pole. They are continuous throughout the body of the magnet. Magnetic lines of force can pass through iron more easily than air, which is why iron is used as a core in electromagnets. Two magnetic lines of force cannot intersect each other, which is why when you try to push two equal magnets (pushing north and north towards each other) they repel. Magnetic field lines tend to contract longitudinally and expand laterally. The magnetic field lines are crowded near the pole where the field is strong and away from the magnet where the field is weak. Say no to plagiarism. Get a tailor-made essay on "Why Violent Video Games Shouldn't Be Banned"? Get an Original Essay Flux density is the amount of magnetic, electric, or other flux that passes through a unit area, and magnetic field strength is the field of force created by moving electric charges and magnetic dipoles. Magnetic field lines, fictitious objects, are conceptualized to indicate the magnetic field on a magnetic material. They provide a visual representation of the magnetic field around a magnetic material. They originate at the north pole and end at the south pole of a magnet. A tangent to a magnetic line indicates the direction of force on a north pole. The magnitude of the force is given in terms of the density of the magnetic lines at the point. The relationship between flux density and field strength is that the greater the density of flux lines the greater the magnetic force. These are called lines of force. Electromagnets also have these lines, however they are electric lines of force and are similar, although the magnetic poles in electromagnetism are replaced by electric charges. Electromagnetic induction is an incredibly useful phenomenon with a wide variety of applications. Induction is used in the generation and transmission of energy. An eddy current is a swirling current created in a conductor in response to a changing magnetic field. The current turns in such a way that it creates a magnetic field that opposes the change, to do this in a conductor the electrons rotate in a plane perpendicular to the magnetic field. Since eddy currents tend to oppose each other, they cause energy loss. Eddy currents transform more useful forms of energy such as kinetic energy into heat. Normally this is less useful in most situations as the loss of useful energy is not desirable, however there are some practical applications for the loss of useful energy. One such application is in the brakes of some trains. When a train brakes, the metal wheels are exposed to the magnetic field of an electromagnet, generating eddy currents in the wheels. This magnetic interaction between the applied field and eddy currents acts to slow down the wheels. The faster the wheels spin, the stronger the effect. This in turn means that as the train slows down, the braking force is reduced, producing the smooth stopping motion felt in trains. Please note: this is just an example. Get a custom paper from our expert writers now. Get a Custom EssayWhen a conductor is passed through a magnetic field, a voltage is generated in it. This voltage will be slightly reduced by the resistance of the conductor, so we talk about the theoretical voltage as if the conductor had no resistance and this is called the force.