The fire alarm demonstrates how a sensor detects a nearby flame and activates a buzzer, while the intruder alarm demonstrates how an IR sensor detects an object near the entrance and triggers an alert. These activities help students understand how sensors respond to changes and produce an electronic output. Suitable for classroom demonstrations, school projects and science exhibitions, this working model encourages observation, problem-solving and scientific curiosity. Students can explain the detection process, identify circuit components and demonstrate basic security concepts. It can also support a Class 12 physics project presentation, depending on school requirements.