Final answer:
Alarms use auditory signals like loud sounds, visual signals like flashing lights, and in nature, even chemical signals to alert occupants or other animals of potential dangers such as fires or the presence of predators.
Step-by-step explanation:
Alarm systems alert occupants through various sensory methods to ensure quick and effective responses to emergencies such as fires or intrusions. A common form of alarm is the smoke detector, which detects the presence of smoke particles using ionization. The Americium-241 inside the smoke detector emits α particles that ionize the air, creating an electrical current. When smoke disrupts this current, it triggers a loud sound to alert occupants.
Additionally, alarms can utilize visual elements like flashing lights, especially in loud environments or to assist those with hearing impairments. In nature, for example, chemical alarm signals can prompt a response in other animals, such as fish releasing chemical compounds when predators are present, signaling danger to others nearby.