The hydrogen line spectrum has four lines that are in the visible range. The red line occurs at 421.7 nm what is the frequency in Hertz?

Answer 1

Given the wavelength (421.7 nm) an asked for frequency, we will use c = f x w

c = speed of light = 3x10⁸ m/sec

w = wavelength = 421.7 nm but we want this in meters, so it will be 421.7x10^-9 m

f = frequency in sec^-1 = Hertz

3x10⁸ m/sec = (421.7x10^-9 m)(w)

w = 3x10⁸ m/sec / 421.7x10^-9 m

w = wavelength = 7.11x10¹⁴ sec^-1