Inductors, What do they do?
The electronic component known as the inductor is best described as electrical momentum. In our water pipe analogy the inductor would be equivalent to a very long hose that is wrapped around itself many times. If the hose is very long it will contain many gallons of water. When pressure is applied to one end of the hose, the thousands of gallons of water would not stare to move instantly.
Inductors, How are they made?
In order to understand how inductors are made, we have to change our water pipe analogy slightly to include the effect of magnetic fields. Consider two pipes filled with water and small magnets attached to the walls of the pipes with rubber bands. The moving magnets, due to the original current, pull the magnets in the second pipe and force a small current to flow.
Inductance, How is it calculated?
Reviewing how coils are made will show the following
1. inductance of a coil is indirectly proportional to the length of the coil.
2. inductance is directly proportional to the cross sectional area.
3. inductance is proportional to the square of the number of turns.
4. Inductance is directly proportional to the permeability of the core material.
Summary
The inductor prevent currents from making any sudden changes by producing large opposing voltages. Magnetic coupling can be used to transform voltages and currents, but power must remain the same. Coil and transformers can be used to select frequencies.