What type of sensor uses ultrasonic sound waves to measure distance to an object?
HC-SR04 is an ultrasonic distance sensor that calculates range by sending out a 40 kHz sonic wave and measuring the echo return time. LDR measures light, and PIR detects motion via infrared.
Which sensor is most widely used in motion-detection security systems to spot human presence based on heat emission?
PIR sensors detect changes in infrared radiation emitted by living bodies, making them ideal for intruder alerts and motion-triggered smart lighting.
What is 'Fog Computing' in the context of IoT architecture?
Fog computing (coined by Cisco) sits between edge devices and centralized cloud data centers, performing local analytics, storage, and low-latency decision making near the edge.
Which of the following is an open-source visual tool developed by IBM for wiring together hardware devices, APIs, and online services in IoT?
Node-RED is a browser-based visual flow editor built on Node.js that simplifies wiring IoT hardware nodes, APIs, and cloud services using a visual drag-and-drop toolkit approach.
In IoT security, what does the term 'Confidentiality' guarantee?
In the CIA triad of security: Confidentiality ensures privacy (data is encrypted and unreadable by unauthorized parties), Integrity prevents tampering, and Availability ensures operational uptime.