What is the energy (in joules) of an ultraviolet photon with wavelength 150 nm what is its frequency?

We can calculate energy by using Planck's equation that is;

E = h c / ʎ

where,

h is the Planck’s constant = 6.626 x 10⁻³⁴ m² kg / s

c is the speed of light = 3 x 10₈ m/s

ʎ is the wavelength of light = 150 nm = 150 x 10⁻⁹ m

Now pot the values in equation;

E = (6.626 x10⁻³⁴ m² kg / s) x (3 x 10⁸ m/s) / (150 x 10⁻⁹ m)

E = 1.325 x 10⁻¹⁸ J

Now by using the following equation we can calculate the frequency;

E = hf

f = E/h

f = 1.325 x 10⁻¹⁸ / 6.626 x 10⁻³⁴

f = 1.9997 x 10¹⁵ Hz