The photoelectric work function for a metal is 4.2 eV. Find the t… - Vidyadip

Question

The photoelectric work function for a metal is \(4.2 eV\). Find the threshold wavelength.

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Answer

\(\phi_0=\frac{h c}{\lambda_0}\)
\(\lambda_0=\frac{h c}{\phi_0}\)
\(\phi_0=4.2 ev =4.2 \times 1.6 \times 10^{-19} J =6.72 \times 10^{-19} J\)
\(\lambda_0=\frac{h c}{\phi_0}=\frac{6.63 \times 10^{-34} \times 3 \times 10^8}{6.72 x 10^{-19}}\)
\(\lambda_0=2.960 \times 10^{-7} m\)
$\lambda _0 = 2960 A^0$

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