what is light ?how it is useful for human being
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Answers
Answer:
We have evolved to not only love light, but to need light: we see best in the light and have limited sight in the darkness; daily exposure to light keeps us healthy and light is already used in a number of therapeutic applications; and since time began, light has allowed us to live productive lives, has kept the ...
Answer:
Light, or Visible Light, commonly refers to electromagnetic radiation that can be detected by the human eye. ... Light can also be described in terms of a stream of photons, massless packets of energy, each travelling with wavelike properties at the speed of light.
Explanation:
Most public health messages of the past century have focused on the hazards of too much sun exposure. UVA radiation (95–97% of the UVR that reaches Earth’s surface) penetrates deeply into the skin, where it can contribute to skin cancer indirectly via generation of DNA-damaging molecules such as hydroxyl and oxygen radicals. Sunburn is caused by too much UVB radiation; this form also leads to direct DNA damage and promotes various skin cancers. Both forms can damage collagen fibers, destroy vitamin A in skin, accelerate aging of the skin, and increase the risk of skin cancers. Excessive sun exposure can also cause cataracts and diseases aggravated by UVR-induced immunosuppression such as reactivation of some latent viruses.