When light is dispersed through a glass prism, it is called a *continuous **spectrum *because the light being diffracted contains many wavelengths. When a spectrum source produces a small number of wavelength components, then a *discontinuous spectrum *is formed. In many cases, the spectrum forms a limited number of wavelength components, observed as colored lines with dark spaces. Those discontinuous spectra are called **atomic spectra.**

Through experimentation, Johann Balmer deduced a formula for the wavelengths of these spectral lines. Balmer's equation was

*v* = 3.2881 x 10^{15}s^{-1}(1/4 - 1/n^{2})

## n >= 3, and goes from right to left

So, in order to find the frequency of the line of the highest wavelength you plug in n = 3, and as you keep going left, n keeps increasing.

## Example

To find the frequency of the light blue light (2nd from the left), you plug in n = 5.

3.2881 x 10^{15}(1/4 - 1/25)

= 3.2881 x 10^{15}(0.21)

= 6.905 x 10^{14}