{"id":4523,"date":"2018-09-05T09:56:53","date_gmt":"2018-09-05T13:56:53","guid":{"rendered":"https:\/\/dronebotworkshop.com\/?p=4523"},"modified":"2023-04-12T12:40:28","modified_gmt":"2023-04-12T16:40:28","slug":"arduino-uv-index-meter","status":"publish","type":"post","link":"https:\/\/dronebotworkshop.com\/arduino-uv-index-meter\/","title":{"rendered":"Arduino UV Index Meter – Measuring UV Light"},"content":{"rendered":"\n

\"Download \"Parts<\/a> \"View<\/a> \"Download<\/a><\/p>\n

Introduction<\/span><\/h2>\n

The Sun.\u00a0 Our closest star resides about 150 million Km (93 million miles) from Earth and without it life itself would simply not be possible here. The Sun provides us with both heat and light, essential for our survival.<\/span><\/p>\n

But the Sun has a bit of an evil side as well. In addition to visible light and heat it also emits radiation across a wide spectrum, some of it in the form of lethal X-rays and gamma rays. \u00a0Fortunately our planet has the Van Allen belts surrounding it, acting like a Star Trek type \u201cshield\u201d that protects us from this deadly radiation.<\/span><\/p>\n

The Sun also emits light across a broad spectrum. At the low end is the Infrared light (which is perceived as heat), followed by the visible light that we are all familiar with. \u00a0And then there is Ultraviolet light at the high end.<\/span><\/p>\n

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Ultraviolet or UV light is filtered to a large degree by the Earth’s Ozone layer, a protective layer of gas in the upper atmosphere that absorbs UV radiation. \u00a0But the ozone layer is not a perfect filter and as a consequence some of the UV makes it through.<\/span><\/p>\n

Humans can tolerate low levels of UV exposure just fine, in fact many of us seek out these UV rays as they are responsible for temporarily darkening the pigment of our skin – in other words a suntan! \u00a0But too much exposure to UV light can cause serious health problems ranging from third degree burns to skin cancer.<\/span><\/p>\n

Whether you\u2019re an avid outdoors person, a diehard sunbather or a parent who is concerned for their child’s welfare knowing the current UV light level can be very important.<\/span><\/p>\n

\"Arduino<\/p>\n

Today in the workshop we will experiment with UV light, both producing it and detecting it. \u00a0We will then build a UV Index meter that is capable of accurately measuring the current UV level.<\/span><\/p>\n

So grab your sunscreen and follow along!<\/span><\/p>\n

Ultraviolet (UV) Light<\/span><\/h2>\n

In 1801 German physicist Johann Wilhelm Ritter observed paper soaked in silver chloride would turn dark when exposed to light rays above the violet end of the visible light spectrum. \u00a0He named these rays “oxidizing rays”, as opposed to the newly discovered \u201cheat rays\u201d which were below red at the bottom end of the visible light spectrum.<\/span><\/p>\n

Now we refer to these areas of the spectrum by different names. The former \u201cheat rays\u201d are now known as \u201cinfrared\u201d radiation, light radiation with a lower frequency than red light. \u00a0And the “oxidizing rays” are now referred to as \u201cultraviolet\u201d radiation, light radiation with a higher frequency than violet.<\/span><\/p>\n

The following chart illustrates the electromagnetic spectrum. Note that ultraviolet radiation is just above visible light in frequency or just below it in wavelength (wavelength is the inverse of frequency).<\/span><\/p>\n

\"Electromagnetic<\/p>\n

As UV light is above violet it is not visible to the human eye, although some birds can see part of the UV spectrum due to an additional color receptor in their eyes.<\/span><\/p>\n

The UV Spectrum<\/span><\/h3>\n

The ultraviolet section of the electromagnetic spectrum extends from 400 nm to 100 nm, just below the X-ray section of the spectrum. \u00a0It is actually divided into three sections:<\/span><\/p>\n