Light of wavelength...... Modern Physics help!
Favorites|Homepage
Subscriptions | sitemap
HOME > Physics > Light of wavelength...... Modern Physics help!

Light of wavelength...... Modern Physics help!

[From: ] [author: ] [Date: 11-05-25] [Hit: ]
25 x 1.6x10^-19) / 6.63x10^-34 = 5.I guess you know what all the symbols mean.......
Light of wavelength 350 nm falls on a potassium surface, and the photoelectrons have a maximum kinetic energy of 1.3 eV.
What is the work function of potassium? The speed of light is 3 × 108 m/s and Planck’s constant is 6.63×10−34J·s.

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

Answer in units of eV.

-
c = f.λ ---------------> f = c / λ

E = hf - φ -------------> sub in 'f'

E = (hc / λ) - φ -------------------> solve for φ

φ = (hc / λ) - E

φ = [(6.63×10^−34)(3x10^8) / (350x10^-9)(1.6x10^-19)] - 1.3

[divided the (hc / λ) by 'e' to get into eV]

φ = 3.55 - 1.3 = 2.25 eV

hf = 2.25 eV

f = 2.25 eV / h = (2.25 x 1.6x10^-19) / 6.63x10^-34 = 5.4 x 10^14 Hz

I guess you know what all the symbols mean.
1
keywords: wavelength,Light,help,Physics,Modern,of,Light of wavelength...... Modern Physics help!
New
Hot
© 2008-2010 http://www.science-mathematics.com . Program by zplan cms. Theme by wukong .