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| Length Measurements |
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| It is the shortest distance between two ends of the body. For measuring lengths, two methods can be employed, namely direct method and indirect method. Direct methods are employed for measuring small lengths by comparing such lengths or distances with an approved standard of length viz. vernier callipers, screw gauge and so on. For long, atomic and astronomical distances, indirect methods are used. The indirect methods are |
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 Echo or reflection method |
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 SONAR method |
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 RADAR method |
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 Triangulation method |
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 Parallax method |
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