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| 7.3 |
Einstein's Photoelectric Theory |
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Einstein's Photoelectric Equation |
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\(\dfrac{1}{2}mv_{maks}^2 = hf-W\)
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At the threshold frequency \(f_0\), kinetic energy = 0, then |
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\(\dfrac{1}{2}mv_{maks}^2=h(f-f_0)\)
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Work function |
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The minimum energy required for a photoelectron to be emitted from a metal surface.
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\(W=hf_0=\dfrac{hc}{\lambda}\)
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Threshold frequency |
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The minimum frequency for a light photon to produce photoelectric effect. |
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| Caesium |
Lithium |
| Work function of caesium, \(W = 2.14\;eV\) |
Work function of lithium, \(W = 2.14\;eV\) |
| Threshold frequency, \(f_0 = 5.16\times 10^{14}\text{ Hz}\) |
Threshold frequency,\(f_0 = 6.03\times 10^{14}\text{ Hz}\)
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| Maximum wavelength to produce photoelectric current, \(\lambda = 579\text{ nm}\) |
Maximum wavelength to produce photoelectric current, \(\lambda = 496\text{ nm}\)
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Photoelectric Effect Applications
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- Solar panel
- Light detectors at the automatic doors
- Image sensor in high resolution cameras
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