# Scalar sensor vs Vector sensor in IoT

This page compares Scalar sensor vs Vector sensor and mentions difference between Scalar sensor and Vector sensor in IoT (Internet of Things). These sensors measure or sense different physical quantities.

## What is Scalar sensor ?

• Definition : The sensor which produce output signal/voltage which is proportional to magnitude of quantity to be measured is known as scalar sensor.
• Examples:
Temperature sensor, Color sensor, pressure sensor, strain sensor etc.

Example-1 : Temperature of a room is measured using scalar sensor (i.e. thermometer or thermocouple) which measures temperature changes irrespective of sensor orientation. The output of temperature sensor is scalar value (e.g. 25 degrees celsius)
Example-2 : Pressure sensor measures pressure exerted by a fluid, and the result is a scalar value (e.g. 101.3 kPa)
Example-3 : Light sensor measures the intensity of light, providing a scalar value (e.g. 500 lux)

## What is Vector sensor ?

• Definition : The sensor which produce output signal/voltage which is proportional to magnitude, direction as well as orientation of quantity being measured is known as Vector sensor.
• Examples:
Sound sensor, image sensor, velocity sensor, acceleration sensor etc.

Example-1 : Acceleration of body is measured using accelerometer which measures component of acceleration of body with respect to x, y, z coordinate axes. Acceleration is a vector quanity. It provides information about the rate of change of velocity along different axes (e.g. 2 m/s2, 3 m/s2, -1 m/s2
Example-2 : Magnetic Field Sensor measures the strength and direction of the magnetic field at a specific location. The output includes both magnitude and direction (e.g., 30 μT north).
Example-3 : Gyroscope measures the rate of rotation around different axes, providing angular velocity as a vector (e.g., 50 degrees per second around the z-axis).

## Difference between Scalar sensor and Vector sensor

The major difference between scalar sensor and vector sensor is based on type of data to be measured. As mentioned above, scalar sensor measures scalar data where as vector sensor measures vecror data. Following table summarize the same.

Parameters Scalar sensor Vector sensor
Measured quantity Scalar quantity (magnitude only) Vector quantity (magnitude and direction)
Output format Single scalar value Multiple values (magnitude and direction components)
Representation Represented by a single number Represented by multiple numbers (components)
Physical property Describes magnitude of the phenomenon Describes both magnitude and direction of the phenomenon
Examples Temperature sensor, Pressure sensor, Light sensor Accelerometer, Magnetic field sensor, Gyroscope

Conclusion : In summary, the key distinction is that scalar sensors measure scalar quantities, such as temperature or pressure, which only have magnitude, while vector sensors measure vector quantities, like acceleration or magnetic field, which have both magnitude and direction.