physics question 1 hw 20

Physics
Tutor: None Selected Time limit: 1 Day

When light of wavelength 322 nm falls on a potassium surface, electrons are emitted that have a maximum kinetic energy of 1.35 eV. What is the work function of potassium? The speed of light is 3 × 108 m/s and Planck’s constant is 6.63 × 10−34 J · s. Answer in units of eV.

What is the cutoff wavelength of potassium? Answer in units of nm.

What is the threshold frequency for potassium? Answer in units of Hz.

Jul 14th, 2015

Thank you for the opportunity to help you with your question!

a) λmaxT = 0.2898x10-2mK => T = 0.2898x10-2mK/λmax =>

=> T = 0.2898x10-2mK/(970x10-9m) => T = 3x10-4 x 107 K => T = 3000 K

b) λmaxT = 0.2898x10-2mK => T = 0.2898x10-2mK/λmax =>

=> T = 0.2898x10-2mK/(145x10-9m) => T = 2x10-3 x 107 K => T = 20,000 K


Please let me know if you need any clarification. I'm always happy to answer your questions.
Jul 14th, 2015

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Jul 14th, 2015
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Jul 14th, 2015
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