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9 Cards in this Set
- Front
- Back
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Static electricity |
When you rub two objects together they become electrically charged as electrons which are transferred from one object to another. The object receiving the electrons becomes negatively charged and the object giving up electrons becomes positively charged. The electric charge is called static electricity. |
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Repulsion and attraction |
When two charged materials are brought together they exert a force on each other. Two materials with the same type of charge repel each other. Two materials with different charges attract each other. |
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Types of current |
A direct current always flows in the same direction cells and batteries supply direct current.
An alternating current changes the direction of flow back and forth continuously and is used for mains electricity. The mains supply of voltage to your home is 230 volts. Alternating current is used for mains supply instead of Direct current because it's easier to generate, it can be distributed more efficiently and only alternating current can be used in a transformer. |
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Resistance |
Resistance=volts÷current. |
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Series circuit |
When two components are connected in Series to a battery: The current flowing through each component is the same The potential difference across the components adds up to the potential difference across the battery The potential difference is largest across components with the greatest resistance |
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Parallel circuit |
In parallel circuits with one component per parallel path: The current flowing through each component depends on the resistance of each component. The total current running from the battery is equal to the sum of the current through each of the parallel components. The current is greatest through the component with the smallest resistance. |
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Electromagnetic induction |
When your move a magnet into a coil of wire a voltage is induced between the ends of the wire because the magnetic field is being cut. If the ends of the coil are connected to make a complete circuit a current will be induced. This is called electromagnetic induction. Moving the magnet into the coils induces a current in one direction. You can induce a current in the opposite direction by moving the magnet out of the coil and moving the other pole of a magnet into the coil. |
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Power |
Power=voltage×current |
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Transformers |
Transformers are used to change the voltage of an alternating current. They consist of 2 coils of wire called the primary and secondary coil wrapped around a soft iron core. When two coils of wire are close to each other a changing magnetic field in one coil caused by changes in the current can induce a voltage in the other. Alternating current flowing through the primary coil creates an alternating magnetic field. This changing field then induces an alternating current in the secondary coil. |
