The document discusses various topics related to magnetism and electromagnetism including ferromagnetic materials like iron, nickel, and cobalt. It explains that moving electrons produce magnetic fields and outlines some key discoveries like Oersted discovering that moving electrons create magnetic fields. It also briefly touches on topics like magnetic domains, magnetic tape, electromagnets, electric motors, generators, and power plants.
The Earth’s magnetic field is thought to originate with moving charges. The core is probably composed of iron and nickel, which flows as the Earth rotates, creating electrical currents that result in the Earth’s magnetic field.
A very highly simplified model of an atom has most of the mass in a small, dense center called the nucleus. The nucleus has positively charged protons and neutral neutrons. Negatively charged electrons move around the nucleus at a much greater distance than is suggested by this simplified model. Ordinary atoms are neutral because there is a balance between the number of positively charged protons and negatively charged electrons.
Fe, Ni, and Co are called ferromagnetic materials. The domains in Ferromagnetic Materials are usually in a random orientation and free to move . The diagram above illustrates how the magnetic domains rearrange when in the proximity of a magnetic field.
An electrical motor is an electromagnetic device that converts electrical energy into mechanical energy. A motor has two working parts, a stationary magnet called a field magnet and a cylindrical, movable electromagnet called an armature. The armature is on an axle and rotates in the magnetic field of the field magnet. The axle is used to do work.
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