What is the frequency of violet light having wavelength 400 nm ?

What is the frequency of violet light having wavelength 400 nm ?
  1. $3.0 \times 10^{14} \mathrm{~Hz}$
  2. $4.0 \times 10^{14} \mathrm{~Hz}$
  3. $7.5 \times 10^{14} \mathrm{~Hz}$
  4. $9.0 \times 10^{14} \mathrm{~Hz}$

Solution

$\begin{aligned} v=\frac{\mathrm{c}}{\lambda} & =\frac{3 \times 10^8 \mathrm{~ms}^{-1}}{400 \times 10^{-9} \mathrm{~m}} \\ & =7.5 \times 10^{14} \mathrm{~Hz}\end{aligned}$

Asked in: MHT CET 2024 (10 May Shift 2)

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