If the light of wavelength 700 nm strikes such a photocathode the maximum kinetic energy, in eV, of the emitted electrons is 0.558 eV.
so - $KE_{max} = hc/lembda} work
threshold when KE = 0
hc/lambda = work = 1240/900=1.38 eV
b) Kemax = hc/lambda - work = 1240/640 -1.38=0.558 eV
What is photocathode?
- A photocathode electrolyte interface can be used in a photoelectrolysis cell as the primary light-harvesting junction (in conjunction with an appropriate electrochemical anode) or as an optically complementary photoactive half-cell in a tandem photoelectrode photoelectrolysis cell (Hamnett, 1982; Kocha et al, 1994).
- In the case of the former, the electrode should ideally harvest photon energy across the majority of the solar spectrum in order to achieve the highest energy conversion efficiency possible.
- In the latter case, however, the photocathode may only be active in a specific band of the solar spectrum in order to generate a cathodic photocurrent sufficient to match the current generated in the photoanodic half-cell.
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Answer:

Explanation:
As per Heisenberg's uncertainty principle we know that

so here we have


now from above equation we have




Explanation:
You can simply subtract the atomic number from the mass number in order to find the number of neutrons. If the atom is neutral, the number of electrons will be equal to the number of protons.
Remember!
1. Your mass number is the total number of neutrons and protons within the atom.
2. Your atomic number is the amount of protons within the atom.
3. For neutral atoms, the electron number is the same as the atomic number.