{"id":15474,"date":"2025-09-29T06:57:15","date_gmt":"2025-09-29T01:27:15","guid":{"rendered":"https:\/\/johnsonfrancis.org\/techworld\/?p=15474"},"modified":"2025-09-29T06:57:17","modified_gmt":"2025-09-29T01:27:17","slug":"how-does-a-hygrometer-work","status":"publish","type":"post","link":"https:\/\/johnsonfrancis.org\/techworld\/how-does-a-hygrometer-work\/","title":{"rendered":"How does a hygrometer work?"},"content":{"rendered":"<iframe loading=\"lazy\" width=\"560\" height=\"315\" src=\"https:\/\/www.youtube.com\/embed\/pxc5S2gCEPs?si=Um8axRt-D3X1oH7a\" title=\"YouTube video player\" frameborder=\"0\" allow=\"accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share\" referrerpolicy=\"strict-origin-when-cross-origin\" allowfullscreen><\/iframe>\n\n<p class=\"wp-block-paragraph\">Any one listening to amateur radio nets would have heard many operators mentioning the humidity percentage in their radio room. I do have one in my radio room, which can measure temperature and humidity. In addition it has a clock and alarm facility as well as an hourly chime. We bought this temperature and humidity meter from Amazon: <a href=\"https:\/\/amzn.to\/44VFYgu\">https:\/\/amzn.to\/44VFYgu<\/a>. Please note that if you buy from this link, Amazon will pay me a small bit as an affiliate, with no additional cost to the buyer. Have you ever wondered how these type of electronic instruments measure humidity? Instrument which can measure humidity is known as a hygrometer.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Hygrometers measure some other quantities like temperature, pressure, mass and mechanical or electrical changes in a substance when it absorbs moisture. From these measured changes, by calibration and calculation they can be used to indicate humidity. When we were at school decades back, we were taught of a hair hygrometer though we never had the chance to see one! Here is a public domain image of a hair tension hygrometer from Wikipedia. Hair is hygroscopic, meaning that it retains moisture and length changes with with humidity. Hair hygrometers used a mechanism to magnify this change and indicate on a dial or scale. Historically there were many other methods of measuring humidity as well.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Electronic devices can measure the temperature of condensation or dew point to assess humidity. Alternatively they can sense changes in electrical capacitance or resistance with changes in humidity. Capacitive hygrometers measure the effect of humidity on the dielectric constant of a polymer or metal oxide. A calibrated capacitive hygrometer can have an accuracy of \u00b12% relative humidities between 5% and 95% relative humidity. Capacitive sensors can tolerate effects of condensation and transient high temperatures. But they are subject to contamination, drift and aging effects.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Resistive hygrometers measure the change in electrical resistance of a material due to changes in humidity. Salts which can absorb moisture easily and conductive polymers can be used as sensors. Resistive sensors are less sensitive than capacitive sensors and require more complex circuitry. The property of the sensor will also depend on temperature and hence they are combined with a temperature sensor. Accuracy against condensation varies depending on the resistive material chosen. Condensation resistant sensor can give an accuracy of \u00b13% relative humidity.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Any one listening to amateur radio nets would have heard many operators mentioning the humidity percentage in their radio room. I do have one in my radio room, which can measure temperature and humidity. In addition it has a clock and alarm facility as well as an hourly chime. We bought this temperature and humidity [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":15478,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[7],"tags":[],"class_list":["post-15474","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-amateur-radio-ham-radio"],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v27.8 - https:\/\/yoast.com\/product\/yoast-seo-wordpress\/ -->\n<title>How does a hygrometer work? - Johnson&#039;s Techworld<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/johnsonfrancis.org\/techworld\/how-does-a-hygrometer-work\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"How does a hygrometer work? - Johnson&#039;s Techworld\" \/>\n<meta property=\"og:description\" content=\"Any one listening to amateur radio nets would have heard many operators mentioning the humidity percentage in their radio room. I do have one in my radio room, which can measure temperature and humidity. In addition it has a clock and alarm facility as well as an hourly chime. 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