What is the Maximum Velocity of Electrons Ejected from Copper by 200 nm Light?

AI Thread Summary
The discussion revolves around calculating the maximum velocity of electrons ejected from a copper plate when illuminated with light of a specific wavelength, 200 nm. The longest wavelength that can cause electron ejection from copper is noted as 243 nm. The relevant formula for this calculation is derived from the photoelectric effect: Ek = hf - φ, where Ek is the kinetic energy of the ejected electrons, h is Planck's constant, f is the frequency of the light, and φ is the work function of copper. To relate this to wavelength, the frequency can be calculated using the formula f = c/λ, where c is the speed of light and λ is the wavelength. The maximum velocity of the ejected electrons is determined to be 6.22 × 10^5 m/s. The conversation also touches on the appropriateness of the forum for homework-related questions, emphasizing the need for participants to demonstrate their problem-solving efforts.
eq123
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i've been trying to figure out this problem..

The longest wavelength of light that causes electrons to be ejected from the surface of a copper plate is 243 nm. What is the maximum velocity of the electrons ejected when light of wavelength 200. nm shines on a copper plate?

the answer is 6.22 × 105 m/s

any ideas?
 
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Read about photoelectric effect.

Ek=hf-φ

Where φ is the work function, the lowest energy that must be supplied to tear off an electron, and hf>φ.
 
Read the forum rules!
This isn't the correct board for homework problems. And you should show some attempt to having solved the problem.
 
Ek=hf-φ
thank you.. but how can i relate this to the wavelength concept?
This isn't the correct board for homework problems.
this is not a homework problem.. it is an old exam question..

i would appreciate any additional information..
 
eq123 said:
thank you.. but how can i relate this to the wavelength concept?

f={c\over\lambda}
 
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