How Do You Determine the Work Function of a Photoemissive Material?

AI Thread Summary
To determine the work function of a photoemissive material, the stopping potential (V) is measured alongside the energy of the incident light (hν). The equation hν = ϕ (cathode) + Ek is used, where Ek represents the kinetic energy of emitted photoelectrons. The proposed formula for calculating the cathode work function, ϕ (cathode) = hν + V - ϕ (anode), is under scrutiny for accuracy. The stopping potential indicates that the cathode collects photoelectrons until it exceeds their kinetic energy. Understanding the relationship between the work function of the anode and the kinetic energy of emitted photoelectrons is crucial for accurate calculations.
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Homework Statement


I need to calculate the work function of a photoemissive material. Light is shone through a photocathode (cathode) and the stopping potential V, is measured between anode (stainless steel) and cathode using a picoammeter)
Following are the data measured/calculated
ν = 1.402 e15 Hz (deuterium lamp, at λ= 214nm)
hν = 5.798 eV
stopping potential, V = 2.44 v
ϕ (anode) = 4.4 eV (stainless steel)

Homework Equations


E = hc/λ = hν
hν = ϕ + Ek

The Attempt at a Solution


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How do I calculate the ϕ (cathode)?
Is the formula ϕ (cathode) = hν + V - ϕ (anode) correct?

stopping potential V is measured in volts, everything else in the above equation is in eV. Any solutions?
 
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The work function (phi) has no meaning for the cathode.
The cathode collects photoelectrons until the stopping potential is
greater than the kinetic energy of the photoelectrons emitted from the anode.
Also, what is the kinetic energy of the emitted photoelectrons as it
relates to the work function of the anode?
 
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