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kobusy [5.1K]
3 years ago
5

Light with a wavelength of 395 nm illuminates a metal cathode. The maximum kinetic energy of the emitted electrons is 0.76 eV .

Part A What is the longest wavelength of light that will cause electrons to be emitted from this cathode
Physics
1 answer:
lutik1710 [3]3 years ago
6 0

Answer:

520.8 nm

Explanation:

We are given that

\lambda=395 nm=395\times 10^{-9} m

1 nm=10^{-9} m

Maximum kinetic energy,K_{max}=0.76 eV=0.76\times 1.6\times 10^{-19} V

1 e=1.6\times 10^{-19} C

We have to find the maximum wavelength of light.

We know that

h\nu=\frac{hc}{\lambda_0}+K_{max}

Where c=3\times 10^8 m/s

h=6.625\times 10^{-34}

6.625\times 10^{-34}\times \frac{3\times 10^8}{395\times 10^{-9}}=\frac{6.625\times 10^{-34}\times 3\times 10^8}{\lambda_0}+0.76\times 1.6\times10^{-19}

6.625\times 10^{-34}\times \frac{3\times 10^8}{395\times 10^{-9}}- 0.76\times 1.6\times10^{-19}=\frac{6.625\times 10^{-34}\times 3\times 10^8}{\lambda_0}

\lambda_0=\frac{6.625\times 10^{-34}\times 3\times 10^8}{6.625\times 10^{-34}\times \frac{3\times 10^8}{395\times 10^{-9}}- 0.76\times 1.6\times10^{-19}}

\lambda_0=5.208\times 10^{-7} m=520.8 nm

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