1.3.3 (k): describe how a range of sensors can be used to input data in a computer system.

Sensors are devices which can read/measure physical properties.

Physical data is what is knows as analogue. This means that it is 

constantly changing and doesn't have a discrete value. 

Analogue data requires some way to interpret. For example, a mercury thermometer requires you to look at the height of mercury.

Temperature can therefor have an infinite number of values.

As humans, we can read these values. However, a computer cannot. The data needs to be converted into a digital format.

This is where the sensors come in! This is done by using an Analogue to Digital Converter (ADC). This device converts physical analogue values into discrete digital values.

Analogue data ➝ ADC ➝ Digital data

When computers or microprocessors are used to control devices, it is necessary to use a Digital to Analogue Converter (DAC).

These are used with an actuator, which is a type of electromechanical output device used to control something. (e.g relay, motor or valve)

Actuators may require a DAC to receive an electric current rather than a digital signal

Digital Data ➝ DAC ➝ Analogue data

One needs to know all 9 different sensors: (just some applications and what a sensor is)