Question

Which of these statements regarding sensors is TRUE?
A) Sensors are input devices.
B) Sensors can be analog as well as digital.
C) Sensors respond to some external stimuli.
D) All of these

Answer 1

A sensor is a device that detects changes in the environment and reacts to some other system's output. A sensor converts a physical phenomenon into a measurable analog voltage (or, in some cases, a digital signal), which is then displayed or sent for reading or further processing.

Complete answer:
A Sensor is a device that detects changes in electrical, physical, or other quantities and produces an output as an acknowledgment of the change in quantity. Electric current or potential or magnetic or radio sensors, Humidity sensor, Fluid velocity or flow sensors, pressure sensors, Thermal or Heat or Temperature sensors, Proximity sensors, Optical sensors, position sensors, Chemical sensor, Environment sensor, Magnetic switch sensor, and so on are the most commonly used different types of sensors.
A speed sensor is a sensor that detects the speed of an object or vehicle.
A temperature sensor is a device that measures temperature using an electrical signal.
A PIR sensor, also known as a Pyroelectric sensor, is an electronic sensor that measures the infrared light radiation emitted by objects in its field of view.
Classification of sensors:
Active and Passive Sensors: Active sensors use an external excitation supply to generate an output signal. Sensors that produce an output signal without the use of an external excitation supply are known as passive sensors.
Analog and Digital Sensors: Analog sensors are those that produce a continuous signal with analog output over time. Digital sensors, on the other hand, are used when data is converted and transmitted digitally.
So, Sensors are input devices that can be both analog and digital. External stimuli elicit a response from sensors.
Thus, option (D) is correct.

Note:
The majority of sensors are electronic (data is converted to electronic data), but some are simpler, such as a glass thermometer that displays visual data. Sensors are crucial in the development of IoT solutions. Sensors are devices that detect and replace external data with a signal that humans and machines can understand.