Chemistry · Structure of atom

Which equation correctly represents Einstein's photoelectric equation?

1. \( h\nu_0 = h\nu + \frac{1}{2}m_e v^2 \)
2. \( h\nu = \frac{1}{2}m_e v^2 - h\nu_0 \)
3. \( h\nu = h\nu_0 + \frac{1}{2}m_e v^2 \)
4. \( \frac{1}{2}m_e v^2 = h\nu_0 \)