Whenever light of wavelength 450 nm is shone on potassium, photoelectrons having stopping potential of 0.52 V are emitted. When the wavelength of the incident light is changed to 300 nm, the stopping potential is 1.90 V. By using only these numbers altogether with the values of the speed of light and the electron charge, do the following.
(a) Determine the work function of potassium
(b) Calculate a value for the Planck's constant.