Given that Platinum has a work function of 6.35 eV, the longest wavelength of light that will cause the ejection of electrons is 198 nm
From the given information:
The very first thing we need to consider is to convert the work function of the given element from Electronvolt (eV) to Joules. (J)
Using the standard form of conversion:
Since 1 eV = 1.6 × 10⁻¹⁹ J
∴
6.35 eV =(6.35 eV × 1.6 × 10⁻¹⁹ J)/1 eV
= 1.016 × 10⁻¹⁸ J
Using the formula for calculating the wavelength;
[tex]\mathbf{E = \dfrac{hc}{\lambda}}[/tex]
where:
Replacing the values:
[tex]1.016 \times 10^{-18} = \dfrac{6.626 \times 10^{-34} \times (3.0 \times 10^8 )\ }{\lambda}[/tex]
[tex]\mathbf{\lambda = 1.956 \times 10^{-7} \ m}[/tex]
Wavelength λ = 196 nm
We can therefore conclude that the longest wavelength of the light is 196 nm
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