1. What is the longest-wavelength EM radiation that can eject a photoelectron from silver, given that the binding energy is 4.73 eV? Is this in the visible range? 2. 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?

1. λ = 2.626 x 10⁻⁷ m = 262.6 nm

This wavelength is not in visible range. It lies in Ultra Violet Region.

2. λ = 5.546 x 10⁻⁷ m = 554.6 nm

This wavelength is in visible range.

Explanation:

The binding energy of in photoelectric effect is also known as work function. The formula for this is given as follows:

Binding Energy = Work Function = hc/λ

λ = hc/Work Function   equation (1)

where,

h = Plank's Constant = 6.626 x 10⁻³⁴ J.s

c = speed of light = 3 x 10⁸ m/s

λ = longest wavelength capable of ejecting electron = ?

(1)

Here,

Work Function = (4.73 eV)(1.6 x 10⁻¹⁹ J/1 eV) = 7.568 x 10⁻¹⁹ J

Therefore,

λ = (6.626 x 10⁻³⁴ J.s)(3 x 10⁸ m/s)/(7.568 x 10⁻¹⁹ J)

λ = 2.626 x 10⁻⁷ m = 262.6 nm

This wavelength is not in visible range. It lies in Ultra Violet Region.

(2)

Here,

Work Function = (2.24 eV)(1.6 x 10⁻¹⁹ J/1 eV) = 3.584 x 10⁻¹⁹ J

Therefore,

λ = (6.626 x 10⁻³⁴ J.s)(3 x 10⁸ m/s)/(3.584 x 10⁻¹⁹ J)

λ = 5.546 x 10⁻⁷ m = 554.6 nm

This wavelength is in visible range.

energy can be converted from one form to another, but it cannot be created or destroyed in ordinary chemical or physical means. do not understand what you are asking but hope this

it is a negative acceleration