After a hypothesis has been selected for your science fair project your next step is to figure out an experiment that will allow you to test your hypothesis.
For example, if your hypothesis is that the material a wire is made up of impacts the resistance of an electrical current then you will need to set up an experiment that tests the resistance in a variety of wire types. There are many tools that you can use when developing an experiment. Some tools are as basic as an Ohm meter or volt meter, while others are more complex.
If you don’t want to spend a lot of money on equipment for your electronics science fair project then you can turn to science fair kits that deal with electronics, like the MX-909 500-in-1 Electronic Lab. These kits provide you with everything that you need to perform multiple experiments for less than buying each piece separately.