Finding Work function and Plank constant

I was confuses because the two equations have the same unkknowns, but we can use either one of the equations and the value for plank constant that we get will be the same because both equations have the same unknowns.In summary, the conversation discusses experiments conducted by Millikan on lithium and the resulting maximum kinetic energies observed with different wavelengths of light. From this data, the work function for lithium and the predicted value of Planck's constant can be calculated. The formula for work function is used twice to solve for both unknowns, as there are two equations and two unknowns. It is noted that both equations have the same unknowns and can be used interchangeably to find the same value for Planck's constant.
  • #1
modphysnoob
3
0

Homework Statement



In experiments on lithium, Millikan observed a maximum
kinetic energy of 0.550eV when electrons were ejected with 433.9nm light. When 253.5nm light was
used, he observed a maximum kinetic energy of 2.57eV. Using these results find
a) the work function for lithium, and
b) the predicted value of Planck’s constant.


Homework Equations


h f = work function + kin_max





The Attempt at a Solution



for finding work function

since work function=( h c)/ wavlenght

so we know c , the speed of light , wavelenght, and plank constant so we can find it

however b) ask us to find plank constant , we confuses me
 
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  • #2
modphysnoob said:
1. since work function=( h c)/ wavlenght

Use that formula twice. You're given two sets of max energy and corresponding wavelength. 2 equations, 2 unknowns (work fn and h).
 
  • #3
Thank you , I just realized that
 

FAQ: Finding Work function and Plank constant

What is the work function and Plank constant?

The work function is the minimum amount of energy needed to remove an electron from the surface of a material. It is denoted by the symbol Φ. The Plank constant, denoted by the symbol h, is a physical constant that relates the energy of a single quantum of electromagnetic radiation to its frequency.

How do you measure the work function and Plank constant?

The work function can be measured by using photoelectron spectroscopy, which involves shining light of different frequencies on a material and measuring the kinetic energy of the emitted electrons. The Plank constant can be measured using various methods, such as the photoelectric effect or blackbody radiation experiments.

What is the importance of knowing the work function and Plank constant?

Knowing the work function and Plank constant is crucial for understanding the properties and behavior of materials at the atomic level. They are also important in various applications such as solar cells, semiconductors, and quantum mechanics.

How do the work function and Plank constant relate to each other?

The work function and Plank constant are related through the equation E=hf, where E is the energy of a single quantum of electromagnetic radiation, h is the Plank constant, and f is the frequency of the radiation. This equation shows that the work function is directly proportional to the Plank constant, meaning that an increase in one will result in an increase in the other.

Can the work function and Plank constant vary for different materials?

Yes, the work function and Plank constant can vary for different materials. The work function depends on the properties of the material, such as its composition and surface structure. Similarly, the Plank constant can vary depending on the method used to measure it and the conditions under which the measurement is taken.

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