Question 2.5: Yellow light emitted from a sodium lamp has a wavelength (λ) of 580 nm. Calculate the frequency (ν) and wave number (v¯) of the yellow light.

Question 2.5: Yellow light emitted from a sodium lamp

Question 2.5: Yellow light emitted from a sodium lamp has a wavelength (λ) of 580 nm. Calculate the frequency (ν) and wave number (v¯) of the yellow light.
Ans 2.5: We know
λ = c/ ν
c = velocity of light (3 × 10⁸ m/s)
λ = Wavelength = 580 nm = 580 × 10^-9 m
ν = c/ λ
ν = 3 × 10⁸ / 580 × 10^-9
 ν = 5.17 × 10¹⁴ s^-1
Thus, the frequency of yellow light emitted from the sodium lamp = 5.17 × 10¹⁴ s^–1
The wave number (v¯) of yellow light is given by expression = 1/λ
= 1/580 × 10^-9 m = 1.72 × 10⁶ m^-1

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