## Einstein's Photoelectric Theory

 7.3 Einstein's Photoelectric Theory

 Einstein's Photoelectric Equation $$\dfrac{1}{2}mv_{maks}^2 = hf-W$$ At the threshold frequency $$f_0$$, kinetic energy = 0, then $$\dfrac{1}{2}mv_{maks}^2=h(f-f_0)$$

 Work function The minimum energy required for a photoelectron to be emitted from a metal surface. $$W=hf_0=\dfrac{hc}{\lambda}$$

 Threshold frequency The minimum frequency for a light photon to produce photoelectric effect.

 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,$$f_0 = 6.03\times 10^{14}\text{ Hz}$$ Maximum wavelength to produce photoelectric current, $$\lambda = 579\text{ nm}$$ Maximum wavelength to produce photoelectric current, $$\lambda = 496\text{ nm}$$

Photoelectric Effect Applications

1. Solar panel
2. Light detectors at the automatic doors
3. Image sensor in high resolution cameras

## Einstein's Photoelectric Theory

 7.3 Einstein's Photoelectric Theory

 Einstein's Photoelectric Equation $$\dfrac{1}{2}mv_{maks}^2 = hf-W$$ At the threshold frequency $$f_0$$, kinetic energy = 0, then $$\dfrac{1}{2}mv_{maks}^2=h(f-f_0)$$

 Work function The minimum energy required for a photoelectron to be emitted from a metal surface. $$W=hf_0=\dfrac{hc}{\lambda}$$

 Threshold frequency The minimum frequency for a light photon to produce photoelectric effect.

 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,$$f_0 = 6.03\times 10^{14}\text{ Hz}$$ Maximum wavelength to produce photoelectric current, $$\lambda = 579\text{ nm}$$ Maximum wavelength to produce photoelectric current, $$\lambda = 496\text{ nm}$$

Photoelectric Effect Applications

1. Solar panel
2. Light detectors at the automatic doors
3. Image sensor in high resolution cameras