Final answer:
In case of the loss of normal electrical power in an aircraft, emergency lighting systems that are usually battery-operated ensure that certain critical lights, like dome lights, remain on. These systems are included in the aircraft design for safety purposes, so that important areas remain illuminated.
Step-by-step explanation:
The question pertains to the functionality of an aircraft's internal lighting system when there is a loss of normal electrical power. In such cases, aircraft are designed with emergency systems that include backup power supplies, such as batteries, to ensure that certain critical lights remain operational.
When normal power is lost, the emergency lighting setup, usually supported by batteries or generators, ensures that dome lights and other crucial lights, particularly those meant for evacuation routes and instrument panels, stay lit. This system is independent of the main power to provide illumination vital for safety. Aircraft maintenance manuals or electrical systems documentation usually outline the specific dome light that will remain active during these scenarios and how the emergency power distribution is routed.
Just like in other vehicles, such as cars where you might observe headlights or compartment lights dimming due to battery resistance when the engine starts, airplanes have similar considerations. However, aircraft have more robust systems to ensure ongoing operation of essential systems in the event of power loss, prioritizing the safety of passengers and crew.