# Ask an Expert: Electric generator

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### Electric generator

Hi. I am m doing a project on a small electric generator using magnets and copper coils. I need to know the following.

1. What are the determining factors affecting the output current?

2. When using copper coils and magnets, are there equations I can use to determine what sizes would be best?

3. Regarding equations above, if I have a desired output, is there such equation to determine the ratio of magnet size and copper coils, etc?

4. How can I increase the output if needed?

5. What magnets a would be best to use for this project?

6. If I want to test this generator on maybe an old household appliance, what would I require

Thank you

1. What are the determining factors affecting the output current?

2. When using copper coils and magnets, are there equations I can use to determine what sizes would be best?

3. Regarding equations above, if I have a desired output, is there such equation to determine the ratio of magnet size and copper coils, etc?

4. How can I increase the output if needed?

5. What magnets a would be best to use for this project?

6. If I want to test this generator on maybe an old household appliance, what would I require

Thank you

### Re: Electric generator

Hello,

Here are the answers to your questions in the order they were asked:

An equation is actually not necessary to find what would just be the best possible/practical size magnet/coil:

A higher gauge (thinner) copper wire (I assume this is what you mean by the size of a copper coil; it is somewhat hard for me to tell based on the wording of your questions) is known to carry a higher electrical resistance than lower gauge (thicker) wire, and as a result would carry less current than a thicker wire. An increase in the overall size of a magnet would correspond with an increase in that magnet's strength (considering the fact that it allows for the alignment of more domains in that magnet).Thus, a larger magnet would result in a higher output current in your generator. Based off these two statements, it can be concluded that, theoretically, the "best" sizes for a magnet and the "best" thickness/gauge for a copper wire used in an electric generator would be the largest and thickest possible (or practical).

I hope that these answers will help you with your generator project. If you have any other questions or would like to provide any more details concerning your project, I will be glad to further help you.

Here are the answers to your questions in the order they were asked:

**"What are the determining factors affecting the output current?":**The main factors affecting output current in a DC generator would be the number of turns of wire in the coil you are using, the strength of the magnet being used (higher strength magnetic field results in more lines of flux, allowing for more of these lines of flux to be "cut" within a given amount of time), and the rate at which the magnetic lines of flux are "cut."**"When using copper coils and magnets, are there equations I can use to determine what sizes would be best?":**An equation is actually not necessary to find what would just be the best possible/practical size magnet/coil:

A higher gauge (thinner) copper wire (I assume this is what you mean by the size of a copper coil; it is somewhat hard for me to tell based on the wording of your questions) is known to carry a higher electrical resistance than lower gauge (thicker) wire, and as a result would carry less current than a thicker wire. An increase in the overall size of a magnet would correspond with an increase in that magnet's strength (considering the fact that it allows for the alignment of more domains in that magnet).Thus, a larger magnet would result in a higher output current in your generator. Based off these two statements, it can be concluded that, theoretically, the "best" sizes for a magnet and the "best" thickness/gauge for a copper wire used in an electric generator would be the largest and thickest possible (or practical).

**"Regarding equations above, if I have a desired output, is there such equation to determine the ratio of magnet size and copper coils, etc?":**I am not sure if I completely understand the question. If you are asking whether or not you could use an equation to find what a magnet's ideal size and gauge of wire would be be based off a given output, I would say you would not be able to derive one, as you would first have to find the mathematical relationship between both magnet size and the thickness of a copper wire as it relates to output current. Furthermore, "size" is a somewhat vague measurement, and would need to be specified and given a definite unit in order to be used in any equation (the same could be said for the thickness of the wire).**"How can I increase the output if needed?":**The answer to this question can be found in the first answer given.**"What magnets a would be best to use for this project?":**Because I do not know how exactly you want/plan to execute your project, I cannot necessarily say what magnets would be best for you. If you would like to give a brief explanation of what kind of generator you are planning to make or what your goals for this project are, then I would be better able to provide you with some relevant/appropriate recommendations.**"If I want to test this generator on maybe an old household appliance, what would I require?":**By this question I assume you mean powering a household appliance. Because this would primarily depend upon the appliance that you have in mind as well as the type of generator you are working with (AC or DC), I unfortunately cannot provide you with a definite answer before these details are given.I hope that these answers will help you with your generator project. If you have any other questions or would like to provide any more details concerning your project, I will be glad to further help you.