Ultraviolet radiation is dangerous because it has a high enough energy to damage skin cells. uv radiation is called ultraviolet because it has a frequency which is higher than violet radiation (purple light). therefore, it has a wavelength which is than violet radiation.

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Ultraviolet radiation has broad range of wavelengths, higher number means greater risk of exposure to UV rays that can be dangerous to skin cells. Sunlight is the main source of electromagnetic radiation and it is transmitted in different wavelengths known as electromagnetic spectrum. This spectrum is divided into several regions in order of decreasing wavelength and increasing energy and frequency. UV radiation has frequency and energy that is higher than purple light or violet radiation and the wavelength of ultraviolet radiation is smaller than violet radiation. 

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