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Chemistry Level 2

The work function of a substance is $4\text{ eV}$ . Find (approximately) the longest wavelength of light that can cause photoelectron emission from this substance.

400\text{ nm}

540\text{ nm}

310\text{ nm}

220\text{ nm}

1 solution

Akshat Sharda
May 27, 2016

$4\text{ eV}=h\nu_{o} =\dfrac{hc}{\lambda_{o}}$

Here $h$ is Planck's constant, $c$ is speed of light, $\nu_{o}$ is threshold frequency and $\lambda_{o}$ is threshold wavelength.

$4\text{ eV}=\dfrac{12400\text{ eV} \text{Å}}{\lambda_{o}}$

Here $\lambda_{o}$ is in Angstrom( $Å$ ).

$\therefore \lambda_{o}=3100 \text{ Å}=310\text{ nm}$

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