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1 MAGNETISM.

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Presentation on theme: "1 MAGNETISM."— Presentation transcript:

1 1 MAGNETISM

2 2 Describe magnetism Investigate applications of magnetism and its relationship to the movement of electrical charge as it relates to • electromagnets • simple motors • permanent magnets electromagnetic induction

3 force of attraction or repulsion due to electron motion.
3 Magnetism is the force of attraction or repulsion due to electron motion.

4 4 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 Materials with most of the domains lined up are considered magnetized.
5 Groups of atoms with magnetic poles aligned are called magnetic domains. Materials with most of the domains lined up are considered magnetized.

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8 The more domains that are aligned, the stronger the magnetic field in the material.
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9 7 Field lines were introduced by michael faraday , who named them ‘’lines of force.’’ Sketch this one

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11 Magnetism From Electricity A 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

12 10 The basic idea behind an electromagnet is extremely simple: By running electric current through a wire, you can create a magnetic field.

13 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.

14 A rotating electromagnet is used in an electric motor to convert electrical energy to mechanical energy. 12

15 When a magnet is moved near a wire, an electric current can be created
When a magnet is moved near 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. 13

16 14 Generating electricity: coil of wire rotated in a magnetic field
magnet is moved near a wire

17 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

18 Which of these correctly identifies both devices illustrated?
16 Which of these correctly identifies both devices illustrated? A Picture A: electric generator; Picture B:electromagnet B Picture A: electromagnet; Picture B: electric motor C Picture A: electric motor; Picture B: electromagnet D Picture A: electric generator;

19 A magnetic field can be found in which
17 A magnetic field can be found in which of the following? A electric motor B sound wave C plastic cord D glass rod

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