Answer
frequency = $5.8\times10^{14} s^{-1}$
Work Step by Step
We know, $frequency = \frac{speed \hspace1mm of \hspace1mm light}{wavelength}$
Here, speed of light = $3\times 10^8 m/s$
Wavelength = 515 nm = $515 \times 10^{-9} m$
So, frequency = $\frac{3\times 10^8 m/s}{515 \times 10^{-9} m}$ = $5.8\times10^{14} s^{-1}$
