What happens to the indicator lamp in a smoke detector if smoke is present?

When smoke is detected by a smoke detector, the indicator lamp illuminates automatically. This is designed as a clear visual signal that there is smoke present, alerting personnel to potential danger. The illumination of the lamp is a quick and effective way to communicate the need for immediate attention and action.

Other options do not accurately represent the operational behavior of a smoke detector. For example, a dimming lamp or flickering indicator would not effectively convey the presence of smoke in a straightforward manner, which is critical during emergencies. Additionally, if the lamp remained off, it would not provide any warning or indication of smoke, defeating the purpose of the smoke detection system. Thus, the automatic illumination of the lamp is a crucial design feature that enhances safety by ensuring individuals are quickly notified when smoke is present.