The difference between moving a magnet through a big coil versus a smaller coil is related to the amount of electrical current that is generated. A larger coil will generate more electrical current than a smaller coil, assuming that all other factors are equal. This is because a larger coil has more surface area for the magnet to move through.
According to Faraday’s law of induction, the magnitude of the induced electromotive force (EMF) is proportional to the rate of change of magnetic flux through the coil. In other words, the faster the magnet moves through the coil, the greater the EMF.
A larger coil will also have more inductance than a smaller coil. Inductance is a measure of how much a coil opposes a change in current. A higher inductance means that it will take more time for the current to change in the coil.
In a moving magnet generator, the magnet is attached to the cantilever, which is the arm that holds the stylus. As the stylus moves through the grooves of the record, the magnet moves back and forth, generating an electrical current in the coil.
If the coil is too large, the inductance will be too high, and it will take too long for the current to change. This will result in a loss of high frequencies.
If the coil is too small, the inductance will be too low, and the generator will not produce enough output voltage. This will result in a weak signal.
The ideal size for the coil will depend on a number of factors, including the type of magnet, the speed of the record, and the desired output voltage.
Here is a table that summarizes the key differences between moving a magnet through a big coil versus a smaller coil:
| Characteristic | Big coil | Small coil |
|---|---|---|
| Amount of electrical current generated | More | Less |
| Inductance | More | Less |
| Effect on high frequencies | Loss of high frequencies | No loss of high frequencies |
| Effect on output voltage | Stronger signal | Weaker signal |
It is important to note that there are other factors that can also affect the amount of electrical current that is generated in a moving magnet generator, such as the strength of the magnet and the distance between the magnet and the coil. However, the size of the coil is one of the most important factors.
