$$f = \frac{c}{\lambda}$$

where:

* f is the frequency in hertz (Hz)

* c is the speed of light in meters per second (m/s)

* λ is the wavelength in meters (m)

In this case, we have:

* λ = 5.56 x 10^-7m

* c = 3.00 x 10^8m/s

So, the frequency of yellow light is:

$$f = \frac{3.00 \times 10^8 \text{ m/s}}{5.56 \times 10^{-7} \text{ m}} = \boxed{5.40 \times 10^{14} \text{ Hz}}$$