photoelectric effect

Question

The work function of a metal is 3.3 eV. What is the maximum wavelength of light that can cause photoelectric emission from this metal?

RankGuru · Accepted Answer

The **Work Function ($\phi$)** corresponds to the minimum energy required to eject an electron. This energy corresponds to a maximum wavelength (threshold wavelength $\lambda_0$):
$E = \frac{hc}{\lambda_0}$
Using the shortcut $E(	ext{eV}) = \frac{1240}{\lambda(	ext{nm})}$:
$3.3 = \frac{1240}{\lambda_0} \implies \lambda_0 = \frac{1240}{3.3} \approx 375.76 	ext{ nm}$
Rounding to nearest significant figure: $376 	ext{ nm}$.
- Light with wavelength **shorter** than $376 	ext{ nm}$ (more energy) will cause emission.
- Light with wavelength **longer** than $376 	ext{ nm}$ will not.

Rank Guru

photoelectric effect

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