Final answer:
In a parallel circuit, if one light bulb burns out, the other bulb will remain lit and the ammeter will show a decrease in total current.
Step-by-step explanation:
In a parallel circuit with two light bulbs, if one bulb burns out, the other bulb will continue to operate normally. This is because in a parallel circuit, each component has its own distinct path for current to travel. Therefore, unlike a series circuit, where the failure of one component affects all others in the circuit, in a parallel circuit, the remaining paths are not interrupted by the failure of one path.
If one bulb burns out, the ammeter, which measures current, may show a decrease in the total current because there's now one less path for the current to travel. However, the other bulb will still receive the same voltage from the battery and will maintain its brightness, assuming the battery and wiring resistance remain constant.