#### Answer

The frequency of the emitted light is $\nu\approx5.09\times10^{14}s^{-1}$

#### Work Step by Step

We would calculate the frequency of the emitted light according to the formula $$\nu=\frac{c}{\lambda}$$
$\nu$: frequency of light
$c$: speed of light in a vacuum $(c\approx2.998\times10^8m/s)$
$\lambda$: wavelength of light
The wavelength of the emitted light is $\lambda=589nm=5.89\times10^{-7}m$
Therefore, the frequency of the emitted light is $$\nu=\frac{c}{\lambda}=\frac{2.998\times10^8m/s}{5.89\times10^{-7}m}\approx5.09\times10^{14}s^{-1}$$