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Electric Current
Page 109
Chapter 9


Making a current

The conventional current travels from the positive terminal of the cell to the negative terminal of
the cell (conventional current)

A wire is made of metal. Inside the metal there are negatively charged electron which are free to
move (delocalised or…

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Current and charge

When charged particles flow past a point in a circuit, we say that there is a current in the
circuit, electrical current is measured in amperes (A) charge is measured in coulombs (C)

For a current of 1A, the charge flow past a point in a circuit…

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Kirchhoff's first law

Current may divide up where a circuit splits into two spate branches. For example, a current of
5.0A may split at a junction or a point in a circuit into two separate current of 2.0A and 3.0A.

Current will not disappear, or with the same respect gain…

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An equation for current

The number density is the number of conduction electrons per unit volume. Copper contains a
large number of conduction electrons

The following equation will allow us to find how fast the electrons have to travel

I = Anev

Here v is the mean drift velocity
Here…

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each electron within the metal experiences an electrical force that causes it to move towards the
positive end of the battery.

If the current increases, the drift velocity must increase. Therefore current and drift velocity are
directly proportional. However if the wire is thinner, the electrons move more quickly so…

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