CONDUCTOR OR INSULATOR
Some solutions conduct electricity better than others do, and to allow scientists to understand how well substances conduct electricity, they came up with a scaling system. The highest level on this system is when solutions conduct electricity very well. This is called a strong electrolyte. The middle level, or when solutions conduct electricity, but not very well, is called a weak electrolyte. The lowest level, or when a solution does not conduct electricity at all is called a non-electrolyte. These levels are purely subjective and are open to interpretation by each scientist. To determine the level of conductivity that a solution has, a scientist uses a electrical conductivity apparatus and uses the brightness of the light bulb to determine the level of which the substance should be.
(The brighter the light bulb, the more conductive the solution, the stronger the electrolyte.)