Given:

Wavelength of Yellow Light = 580 nm.

To Find Frequency of the light:

We know the following basic relation,

Speed of Light = [Frequency] × [Wavelength]

We know speed of light = 3×10⁸ m/s

Frequency, v = [3×10⁸] / [580 × 10^-9]

v = 5.17×10¹⁴ Hz

Wave Number is defined as the number of wavelengths which can be accommodated in one centimetre of length in the direction of propagation.

Wave Number for Yellow Light = [1] / [λ]

= [1] / [580 × 10^-9]

= 1.7 × 10⁶ m^-1

Therefore, the frequency of yellow light is 5.17×10¹⁴ Hz and the wave number of yellow light is 1.7 × 10⁶ m^-1