Respuesta :
The work function is 4.74eV if light frequency [tex]1.40 X 10^{15}[/tex] Hz strike a surface causing photoelectrons to leave with a KE of 1.05 eV.
What are photoelectrons?
When light whose frequency is more than the threshold frequency incident on the metal, electrons are emitted. Such electrons are called photoelectrons.
The photoelectric effect is a phenomenon in which a beam of light is projected towards a metal plate and this leads to the ejection of electrons from the metal. The minimum amount of energy required for this ejection of electrons is known as the work function. When the energy of the light beam is less than the work function, then the electrons are not emitted.
The photoelectric effect is represented by the equation:
E = φ + KE where
E = energy of the incident photons
KE = kinetic energy of photoelectrons
φ = Work function of the metal
This can also be written in terms of frequency as:
h = h₀ + [tex]\frac{1}{2}[/tex]mv²
h₀= frequency of the incident light beam
m = mass of the electron
v = velocity of the electron
h = Plank's constant 6.623 x 10⁻³⁴Js
Conversion factor: 1eV = 1.602 x 10⁻¹⁹ J
So, 1.05eV = 1.682 10⁻¹⁹ J
Using the formulas,
(6.623 x 10⁻³⁴Js)(1.40x10¹⁵ s⁻¹) = φ + 1.682 x 10⁻¹⁹ J
(9.272 x 10⁻¹⁹) - (1.682 x 10⁻¹⁹) = φ
φ = 7.590 x 10⁻¹⁹ J = 4.74 eV
Hence, the work function is 4.74eV if light frequency 1.40x10^15 Hz strike a surface causing photoelectrons to leave with a KE of 1.05 eV.
Learn more about work function here:
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