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1. MAGNETISM. 2. Describe magnetism. 3. Magnetism is the force of attraction or repulsion due to electron motion. Magnets have two poles, a north pole and a south pole. Unlike magnetic poles attract each other, while like magnetic poles repel each other. 4. 5.
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1 MAGNETISM
2 Describe magnetism
3 Magnetism is the force of attraction or repulsion due to electron motion.
Magnets have two poles, a north pole and a south pole. • Unlike magnetic poles attract each other, while likemagnetic poles repel each other. 4
5 • Groups of atoms with magnetic poles aligned are called magnetic domains. • Materials with most of the domains lined up are considered magnetized.
The more domains that are aligned, the stronger the magnetic field in the material. 6
7 Field lines were introduced by michael faraday , who named them ‘’lines of force.’’ Sketch this one
Magnetism From ElectricityA connection between electricity and magnetism was discovered (accidentally) over 100 years ago, it was noticed that a compass needle is deflected when brought into the vicinity of a current carrying wire. Thus, currents can induce a magnetic field. An electromagnet is simply a coil of wires which, when a current is passed through, generate a magnetic field, as below. 9 Current gives rise to magnetic fields, just as electric charge gave rise to electric fields Electromagnet
11 Electromagnets Electricity through the coiled wire creates a magnetic field which induces magnetism in the iron core. The domains in the core become aligned with the magnetic field of the coil.
A rotatingelectromagnet is used in an electric motor to convert electrical energy to mechanical energy. 12
13 When a magnet is movednear a wire, an electric current can be created. This process is called electromagnetic induction. Electromagnetic induction is used in the operation of a generator, a device that converts mechanical energy to electrical energy. In a generator, an electric current is produced when a coil of wire is rotated in a magnetic field.
14 • Generating electricity: • coil of wire rotated in a magnetic field • magnet is movednear a wire
15 The use of magnetic waves to make pictures of the inside of the body. Using a large magnet, radio waves, and a computer, an MRI produces two-dimensional and three-dimensional pictures. July 3, 1977
16 Which of these correctly identifies both devices illustrated? APicture A: electric generator; Picture B:electromagnet BPicture A: electromagnet; Picture B: electric generator CPicture A: electric motor; Picture B: electromagnet DPicture A: electric generator; Picture B: electric motor
17 A magnetic field can be found in which of the following? A electric motor B sound wave C plastic cord D glass rod