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Transcript
Section 8 - 3 Transformers and Charges in Magnetic Fields Atoms in a magnet are aligned according to their magnetic domains. Electromagnetic Induction is the production of a current in a conducting circuit by a change in the strength, position, or orientation in an external magnetic field. This is the reason generators and electric motors work. In an AC generator, when charges experience the maximum magnetic force, the current increases. Also in an AC generator, the magnitude of the current produced depends on the orientation of the loop in a magnetic field. The current is at a minimum when the loop is perpendicular to the magnetic field. The amount of current produced will vary with time. Pushing a magnet through an electric field requires work. The greater the electric field, the stronger the force required to push the magnet through the electric field. When a charge moves along or opposite the direction of the magnetic field lines, the magnetic force is zero. When a wire is moving perpendicular to a magnetic field, the force on the charges is at a maximum. When a wire is moving parallel to a magnetic field, no current is induced in the wire. Transformers are devices that can change one alternating current voltage into another alternating current. Transformers can increase or decrease voltage. They change both the amperage and the voltage of an electric current – when one increases, the other decreases. There are two coils of wire inside a transformer. The primary coil uses the input electricity. The secondary coil creates the output electricity. In a step-up transformer, the number of turns of wire is greater in the secondary coil than in the primary coil, and the output voltage exceeds the input voltage. In a step-down transformer, this is the opposite.