Answer:
The light bulb will dim if the solution is a poor conductor.
Step-by-step explanation:
In an apparatus for testing the conductivity of solutions, the light bulb will glow brighter if the solution is a good conductor, and it will be dimmer or not glow at all if the solution is a poor conductor. This is because a good conductor allows for the flow of electric current, which allows more electricity to reach the bulb and make it brighter. A poor conductor, on the other hand, restricts the flow of electric current, which results in less electricity reaching the bulb, causing it to be dimmer or not glow at all.