1. Tardigrade
  2. Question
  3. Physics
  4. Work function of lithium and copper are respectively 2.3eV and 4.0eV. Which one of the metal will be useful for the photoelectric cell working with visible light ? (h = 6 . 6 × (10)- 34 J - s , c = 3 × (10)8 m / s)

Question Error Report

Thank you for reporting, we will resolve it shortly

Back to Question

Q. Work function of lithium and copper are respectively $2.3eV$ and $4.0eV.$ Which one of the metal will be useful for the photoelectric cell working with visible light ? $\left(h = 6 . 6 \times \left(10\right)^{- 34} J - s , c = 3 \times \left(10\right)^{8} m / s\right)$

NTA AbhyasNTA Abhyas 2020

Solution:

From $\lambda _{0}=\frac{12375}{W_{0}}$
The maximum wavelength of light required for the photoelectron emission, $\left(\left(\lambda \right)_{0}\right)_{Li}=\frac{12375}{2 . 3}=5380\overset{o}{A}$
Similarly $\left(\left(\lambda \right)_{0}\right)_{Cu}=\frac{12375}{4}=3094\overset{o}{A}$
since the wavelength $3094\overset{o}{A}$ does not in the visible region, but it is in the ultraviolet region. Hence to work with visible light, lithium metal will be used for photoelectric cell.