# Chemistry

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## Electric current in metals

1) The electric charges

There are two kinds of electric charges:
- Positive electrical charges (+)
- Negative electrical charges (-)

These electrical charges are comparable to north and south poles of magnets: identical poles repel while different poles attract.
We can see a similar phenomenon with electric charges:

- Electrical charges of same sign repel (two negative charges repel each other or two positive charges repel each other).
- Electrical charges of opposite signs attract (positive charge and negative charge attract).

2) The electric charge of electrons

Electrons are electrically charged particles:
Each electron carries a negative elementary charge denoted - e.
The term " elementary " means that there is no electric charge smaller.

3) Electric current in metals

If a metal is a part of an electrical circuit including a generator, the free electrons are influenced by positive and negative terminals of the latter:
Because of their negative charge, electrons are repelled by the negative terminal of the generator and are attracted by its positive terminal.

The free electrons are set in motion and this movement constitutes the electric current.
The free electrons move from the negative to the positive terminal: that is the opposite of conventional direction of electric current

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