Cursed
Nov22-09, 01:04 PM
1. The problem statement, all variables and given/known data
The work function of chromium metal is 7.2 x 10-19 J. What is the maximum speed an electron can be moving if it is ejected from chromium metal by light of wavelength 250 nm? (Answer: u= 4 x105 m/s)
2. Relevant equations
\Phi = h v_{0}
KE = h v_{light} - \Phi = \frac{m_{e} u^{2}_{e}}{2}
\Delta E_{light}= \Phi + KE
h is Planck's constant
v_{0} is the characteristic frequency
m_e is the mass of an electron (9.1 x 10-31 kg)
u_e is the speed of the electron
3. The attempt at a solution
7.2\times10^{-19} J = \frac{(9.1\times10^{-31} kg) (u^{2}_{e})}{2}
u_e \approx 1.3 \times 10^6 m/s
The work function of chromium metal is 7.2 x 10-19 J. What is the maximum speed an electron can be moving if it is ejected from chromium metal by light of wavelength 250 nm? (Answer: u= 4 x105 m/s)
2. Relevant equations
\Phi = h v_{0}
KE = h v_{light} - \Phi = \frac{m_{e} u^{2}_{e}}{2}
\Delta E_{light}= \Phi + KE
h is Planck's constant
v_{0} is the characteristic frequency
m_e is the mass of an electron (9.1 x 10-31 kg)
u_e is the speed of the electron
3. The attempt at a solution
7.2\times10^{-19} J = \frac{(9.1\times10^{-31} kg) (u^{2}_{e})}{2}
u_e \approx 1.3 \times 10^6 m/s