Cells and Betteries
Both primary cells and storage batteries produce electrical energy through the expenditure of chemical energy. In a primary cell, the chemical energy has its origin in the cell, and it is not reversible, so when the chemical reaction is complete, the battery is no longer useful. In a storage battery, the chemical reaction can be reversed by the application of direct current electricity, providing for a longer life span of the battery.
Primary Cells
Primary cells operate by the expenditure of chemical energy in a reaction of conductors dissimilar metals through an electrolyte a nonmetallic aqueous conductor. Primary cells are also called voltaic cells after the Italian scientist Alessandro Volta who discovered the principle by which they operate in 1800. From Volta also comes the word volt and related terms.
Primary cells are classified as either wet cells or dry cells, but even a dry cell must have some moisture in the chemical paste in order for it to serve as an electrolyte. Primary cells produce electrical energy by the flow of ions (positively or negatively charged atoms) between two dissimilar metals.
Electric Motors
The purpose of the generator is to convert mechanical energy into electrical energy, whereas the purpose of the electric motor is to convert electrical energy into mechanical energy. In mechanical design, the generator and the simple DC motor do not differ essentially from each other. Each has an armature rotating in a magnetic field. In the generator, the armature is caused to rotate by some external mechanical force, and electricity is generated in the armature coils. In the simple DC motor, the armature is an electromagnet serving as a filed. When current from a generator or other source is led into the motor, two magnetic fields are produced: one in the armature and one in the field magnet. It is the reaction between these two magnetic fields- the magnetic flux of the field poles-that causes the armature of the electric motor to rotate.
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