The wavelength of blue light is $480 \mathrm{~nm}$. What is frequency of this light?

The wavelength of blue light is $480 \mathrm{~nm}$. What is frequency of this light?
  1. $4.8 \times 10^9 \mathrm{~Hz}$
  2. $2.25 \times 10^{14} \mathrm{~Hz}$
  3. $6.25 \times 10^{14} \mathrm{~Hz}$
  4. $5.25 \times 10^9 \mathrm{~Hz}$

Solution

The correct option is A \(6.25 \times 10^{14} \mathrm{~Hz}\)
Given that:
wavelength \(\lambda=480 \mathrm{~nm}=480 \times 10^{-9} \mathrm{~m}\)
\(\mathrm{c}=3 \times 10^8 \mathrm{~m} / \mathrm{s}\)
We know, \(\mathrm{c}=\mathrm{v} \lambda\)
\(v=\frac{c}{\lambda}=\frac{3 \times 10^8}{480 \times 10^{-9}}=6.25 \times 10^{14} \mathrm{~s}^{-1} \text { or } 6.25 \times 10^{14} \mathrm{~Hz}\)

Asked in: MHT CET 2021 (22 Sep Shift 1)

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