Thanks so much for the links.
Now I know I want to do my science fair project on ferrofluids but I don't know exactly what kind of experiment to conduct or what the judges usually expect. I was thinking I could try different carrier fluids, precipitation or coating methods when creating the ferrofluid and then measure/experiment with its heat capacity, viscosity or other physical properties. I don't really know how these tests are conducted or what materials are required so I don't know if I will be able to do them.
And do you think I could effectively test a transformer using a ferrofluid like they are used in loud speakers? It doesn't seem likely but what kind of a project do you think is best or can you recommend some other things I could try?