Radiation Types & Attenuation: Alpha ($\alpha$) particles are $^4_2\text{He}$ nuclei stopped by paper; Beta ($\beta$) are fast electrons stopped by aluminum; Gamma ($\gamma$) photons follow Beer-Lambert attenuation $I = I_0 e^{-\mu x}$.
Photoelectric Effect: Einstein's photoelectric equation is $K_{\max} = h\nu - \Phi = \frac{hc}{\lambda} - \Phi$. Below cutoff threshold $\nu_0 = \Phi / h$, no electrons are emitted regardless of light intensity.
Stopping Potential: The retarding voltage required to halt the fastest photoelectrons is $e V_s = K_{\max}$.
Operating Instructions: Use the sidebar tab switcher to explore Alpha, Beta, Gamma radiation penetration and the Photoelectric threshold experiment.