| | Input Devices : Sensors | 
|
|
A sensor is a device which measures a physical quantity such as the temperature and then sends a voltage to the computer representing the quantity. Sensors can be either analogue or digital :
Digital : Sensors are either on or off. For example a switch of pressure pad.
Analogue : Sensors can measure a range of values. The size of the voltage the sensor produces is determined by the size of the quantity that the sensor has measured. For example if a cold temperature is measured a small voltage will be sent, whilst if a hot temperature is measured a larger voltage will be sent.
There are lots of different sensors available, each of which is designed to measure a specific quantity. Examples of sensors include :
| Sensor | Type | Quantity Measured | Application |
| Temperature sensor | Analogue | How hot/cold it is. | Monitoring the temperature of a science experiment. |
| Light sensor | Analogue | How light/dark it is. | Turning street lights on when it is dark. |
| Pressure Pad | Digital | If a pad is being pressed. | Detecting cars arriving at a car park barrier. |
| pH sensor | Analogue | The acidity of a liquid. | Monitoring river pollution. |
| Button | Digitial | If the button is being pressed. | Obtaining a ticket at a car park entry barrier. |
| Light Gate | Digital | Detects an object passing through the gate. | Measuring the speed or acceleration of objects. |
Sensors are usually used in data logging and control systems.
GCSE ICT Companion 04 - (C) P Meakin 2004