Calculate the frequency of visible light having a wavelength of 686 nm. (c = 3.00 × 108 m/s)

Given: Wavelength λ = 686 nm convert to meter λ = 6.86 x 10⁻⁷ m

Velocity of light c = 3.00 x 10⁸ m/s

Required: Frequency f = ?

Formula:   f = c/λ

                 f = (3.00 x 10⁸ m/s)/(6.86 x 10⁻⁷ m)

                 f = 4.37 x 10¹⁴ Hz or

                 f = 437 Terahertz