Question

Find the longest-wavelength photon that can eject an electron from potassium, given that the binding energy is 2.24 eV. Is this visible EM radiation?

a) 825 nm, Yes
b) 554 nm, No
c) 1030 nm, No
d) 422 nm, Yes

Answer 1

The longest-wavelength photon that can eject an electron from potassium is approximately 554 nm, which is in the visible range of the electromagnetic spectrum.

Step-by-step explanation:

The longest-wavelength photon that can eject an electron from potassium can be found by using the equation:

Energy of Photon = Binding Energy

Since the binding energy is given as 2.24 eV, we can convert it to joules by multiplying it by the conversion factor of 1.6 × 10^(-19) J/eV. This gives us a binding energy of 3.58 × 10^(-19) J.

The energy of a photon can be calculated using the equation:

Energy of Photon = Planck's constant × Speed of Light / Wavelength

By rearranging this equation, we can solve for the wavelength:

Wavelength = Planck's constant × Speed of Light / Energy of Photon

Using Planck's constant (6.63 × 10^(-34) J·s) and the speed of light (3 × 10^8 m/s), we can plug in the values and solve for the wavelength. The longest-wavelength photon that can eject an electron from potassium is approximately 554 nm, which is in the visible range of the electromagnetic spectrum. Therefore, the answer is option b) 554 nm, No.