Given,
550 nm is the wavelength\(=550\times {{10}^{-9}}m\)
\(c=3\times {{10}^{8}}m/s\) is the speed of light.
We are aware of this.
Frequency = Light Speed / Wavelength
Therefore,
Frequency of yellow light of wavelength \(=\frac{3\times {{10}^{8}}}{550\times {{10}^{-9}}}\)
\(=5.4\times {{10}^{14}}Hz\)