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Saturday, April 18, 2009
9:49 PM
Quantum Physics Pre Lecture Quiz @_@
Hmm looks like our blog died again. *attempts to revive it*
heh, technically i'm not posting the answers. Just in case Mrs Leo actually comes here...
1. A clean plate, made of metal with work function energy of 2.36 eV, is illuminated with ultra violet light of wavelength 370 nm. What is the maximum energy of emitted photoelectrons?
Energy of photon = 370 x 10^-9 x h
h=planck's constant= 4.136 x 10^-15 eVs
Maximum energy of emmitted photons = (370 x 10^-9 x 4.136 × 10^−15) - 2.36
2. In a series of photoelectric emission experiments, metals with different work functions `phi`were illuminated with light of different frequencies f and intensities I. The maximum kinetic energy of photoelectrons in each experiment depends on
"Increasing the intensity of the light beam...does not increase the energy that each electron possesses." -wikipedia
3. Which of the following gives an estimate of the minimum frequency of visible light?
v= c / lambda
(3x10^8) / (400x10^-9)
4. Which one of the following is a correct statement of an observation of the photo-electric effect?
- The higher the work-function of the metal, the LOWER will be the maximum kinetic energy of the emitted photo-electrons.
- The stopping potential is DEPENDENT on the wavelength of the incident radiation.
- Regardless of the incident INTENSITY, no photo-emission will take place unless the FREQUENCY is above a certain threshold value.
5. The frequency of a 5 MeV gamma-ray is
E=hv
E/h = v
v = (5x10^6) / [4.136 × 10^−15 eVs]
sianz i calculated the last question wrong.
-sy
Credits
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