Hygrometer is an instrument used for measuring the value of humidity. It is also known as psychrometer. Generally, the output of hygrometer is used to indicate relative humidity. Several material exhibit changes in electrical properties that are caused by humidity. These are frequently used in transducers that are designed and calibrated to read relative humidity directly.
The types of hygrometer which are given below,
• Resistive hygrometer
• Capacitive hygrometer
• Microwave hygrometer
• Aluminium oxide hygrometer
• Crystal hygrometer
• Hair hygrometer
Material used in hygrometer: hygroscope salt, aluminium oxide, quartz crystal lithium chloride,Hair, etc.