If the wavelength of light is 4000˚A, then the number of waves in 1mm length will be _____ .
A
25
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B
2500
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C
250
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D
25000
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Solution
The correct option is B2500 Wave number ¯ν=1λ=14000×10−10=2.5×106m−1 Number of waves in 1mm (i.e., 10−3m) length, N=¯ν×10−3=2.5×106×10−3=2500 So, option B is correct.