Unit c electrical principals & technologies notes(cells & batteries)

1. Cells & Batteries

2. Cells & Batteries
 Electrochemical Cell: A device that converts chemical energy into
electrical energy and produces direct current.

3. Electrochemical Cell
 Electrochemical Cell:
 They have two
electrodes made of
different metals, and
a conducting electrolyte
(that can form ions).

4. Electrochemical Cell
 A chemical reaction happens in a cell, where
the electrons are removed from one
electrode by the electrolyte and are sent to
the other electrode.
 The electrodes are connected to terminals.
The “+ terminal” is connected to the
electrode that lost its electrons and the “-
terminal” is connected to the electrode that
gained electrons.

5. Electrochemical Cell
 There are 2 types of
electrochemical cells: dry and wet
cells
 dry cells have a paste for an
electrolyte
 wet cells have a liquid electrolyte
(usually a strong acid, which
makes them dangerous)

6. Electrochemical Cell
 Primary Cell: chemical reaction is
irreversible and you throw them
away when they die
 Secondary Cell
(Storage/Rechargeable Cell): can
be restored by using another
source of electricity (electrons
can flow in the opposite
direction)

7. Batteries
 Battery: a combination of several
cells that are sealed in a case with
only 2 terminals instead of a pair
of terminals for each cell
 9 volt and the 6V flashlight
“batteries” are true batteries.
The common AA, AAA, C and D
size “batteries” are single cells –
not batteries.

8. Electroplating

9. Electroplating
 Electrochemistry: the study of chemical processes that cause
electrons to move. It is the study of chemical reactions that create
electricity.
 Electroplating: using electrochemical reactions to deposit a very
thin layer of metal onto the surface of another material.