![]() ![]() Therefore, UV-C from the sun does not affect people. The sun emits UV-C but it is absorbed in the ozone layer of the atmosphere before reaching the earth. The shortwave UV radiation (UV-C) poses the maximum risk. The severity of the effect depends on the wavelength (see Figure 2), intensity, and duration of exposure. In medical practice, one example is UV lamps can be used for treating psoriasis (a condition causing itchy, scaly red patches on the skin).Įxcessive exposure to ultraviolet radiation is associated with different types of skin cancer, sunburn, accelerated skin aging, as well as cataracts and other eye diseases. It stimulates vitamin D production in the body. Some UV exposure is essential for good health. What are some health effects of exposure to UV radiation? Back to top Workers at Potential Risk from Exposure to UV Radiation Table 3 gives examples of devices which employ UV radiation. Table 2 gives some examples of occupations with a potential risk of ultraviolet exposure. Different UV wavelengths and intensities are used for different purposes. UV radiation is widely used in industrial processes and in medical and dental practices for a variety of purposes, such as killing bacteria, creating fluorescent effects, curing inks and resins, phototherapy and suntanning. Man-made ultraviolet sources include several types of UV lamps, arc welding, and mercury vapour lamps. Sunlight is the greatest source of UV radiation. What are some sources of ultraviolet radiation? Back to top UV radiation is divided into three wavelength ranges: UV radiation has shorter wavelengths (higher frequencies) compared to visible light but has longer wavelengths (lower frequencies) compared to X-rays. For example, gamma rays are used in cancer therapy to kill cancerous cells and infrared light can be used to keep you warm. For radiation in the UV region of the spectrum, wavelengths are measured in nanometers (nm), where 1 nm = one millionth of a millimetre.ĭifferent wavelengths of electromagnetic radiation cause different types of effects on people. Wavelength is the length of one complete wave cycle. The waves can be described by their wavelength or frequency and their amplitude (the strength or intensity of the wave). Electromagnetic radiation is transmitted in the form of waves. In scientific terms, UV radiation is electromagnetic radiation just like visible light, radar signals and radio broadcast signals (see Figure 1). The ultraviolet region starts right after the violet end of the rainbow. The light that enables us to see things is referred to as visible light and is composed of the colours we see in a rainbow. Ultraviolet (UV) radiation is similar to visible light in all physical aspects, except that it does not enable us to see things. Sound travels at about 340 metres per second.What is ultraviolet radiation? Back to top Wave speed is measured in metres per second ( \(m\,s^\) ). The speed (or sometimes you might see it called velocity ) of a wave ( \(v\) ) is how far the wave travels in a certain time. For water waves and sound waves the unit hertz is usually good enough but radio and TV waves have such a high frequency that the kilohertz ( \(kHz\) ) or even the megahertz ( \(MHz\) ) are better units. It is not a distance travelled by waves, nor is it a speed, although it is linked to both of these quantities. We normally use a time of one second, so this gives frequency the unit hertz ( \(Hz\) ), since one hertz is equal to one wave per second.ĭon't get confused with this quantity frequency. The frequency ( \(f\) ) of a wave is the number of waves passing a point in a certain time. Wavelength is also measured in metres ( \(m\) ) - it is a length after all. (The symbol is a Greek letter, 'lambda'.) To avoid confusion, it is best to measure wavelength from the top of a crest to the top of the next crest, or from the bottom of a trough to the bottom of the next trough. The wavelength, \(\lambda\), of a wave is the distance from any point on one wave to the same point on the next wave along. The greater the amplitude of a wave then the more energy it is carrying. Amplitude is measured in metres ( \(m\) ). Be careful with this quantity - the centre line is not always given in a diagram. ![]() The amplitude ( \(a\) ) of a wave is the distance from the centre line (or the still position) to the top of a crest or to the bottom of a trough. Sine wave showing peaks, troughs and wavelength You need to know about these quantities used in waves - what they mean, the symbols used for them and the units used to measure them. Frequency, wavelength, amplitude and wave speed ![]()
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