Need some help with this question

Question

The human eye is sensitive to blue light having a frequency of about 6.4  10¹⁴ Hz (a wavelength of about 475 nm). What is the energy in joules of the photons associated with this light?



Answer 1

Planck’s constant (h) is the proportionality constant between a photon’s frequency in Hz (1 Hz = 1 s^-1) and energy in Joules. The value of h is 6.62607015×10⁻³⁴ J⋅Hz⁻¹.

The energy of a photon (light) with frequency of 6.4 x 10¹⁴ Hz  is therefore

(6.62607015×10⁻³⁴ J⋅Hz⁻¹)(6.4 × 10¹⁴ Hz) = 42 × 10^-20 J = 4.2 × 10^-19 J.