Question

The threshold wavelength for potassium is 564 nm. Calculate the work function for potassium and the stopping potential when light of wavelength 400 nm is used.

a) Work function = 1.40 eV, Stopping potential = 1.72 V
b) Work function = 1.72 eV, Stopping potential = 1.40 V
c) Work function = 1.32 eV, Stopping potential = 2.22 V
d) Work function = 2.22 eV, Stopping potential = 1.32 V

Answer 1

The work function for potassium is 2.20 eV and the stopping potential when light of wavelength 400 nm is used is 0.867 V.

Step-by-step explanation:

To calculate the work function for potassium, we can use the formula:

Work Function = Planck's constant * (Speed of Light / Threshold Wavelength)

Using this formula with the given threshold wavelength of 564 nm, we can calculate the work function to be 2.20 eV.

The stopping potential can be calculated using the formula:

Stopping Potential = (Planck's Constant * Speed of Light) / (Work Function - (Energy of Incident Photon / Elementary Charge)

Using this formula with the given wavelength of 400 nm, we can calculate the stopping potential to be 0.867 V.