1. The Professional Development Service for Teachers is funded by the Department of Education and Skills under the National Development Plan Photoelectric Effect T.T.

2. PDST Resources for Leaving Certificate Physics 2 - - - - - - - - - - - - Negatively Charged Electroscope Photoelectric Effect UV When UV shines on the cap… …the leaves collapse …showing the charge is gone

3. PDST Resources for Leaving Certificate Physics 3 + + + + + + + + + + Positively Charged Electroscope Photoelectric Effect UV When UV shines on the cap… …nothing happens

4. PDST Resources for Leaving Certificate Physics 4 Photoelectric Effect A Electromagnetic radiation Circuit used to analyse circuit: Radio / μ-wave / IR / Visible / UV / X-ray / γ-ray Spectrum Low freq. High freq. threshold frequency f o Current flowsNo current Under f o (No current) Over f o (Current) Increase fNo effect Increase intensity No effectIncreases current (of varying frequency and intensity)

5. PDST Resources for Leaving Certificate Physics 5 Photoelectric Effect: Einstein’s explanation A Electromagnetic radiation Circuit used to analyse circuit: Light is a beam of particles (photons) Each photon hits one electron If the electron gains enough energy, it escapes The more electrons, the bigger the current -------- electrons travel to the anode

6. PDST Resources for Leaving Certificate Physics 6 Photoelectric Effect: Einstein’s Photoelectric Law A Electromagnetic radiation Circuit used to analyse circuit: Energy in each photon Energy electrons need to escape (called the work function) Kinetic Energy Photon (containing energy, E in ) hits electron electron uses energy, Φ, to escape electron crosses gap with energy, E k

7. PDST Resources for Leaving Certificate Physics 7 Electromagnetic radiation Circuit used to analyse circuit: A Energy in each photon Energy electrons need to escape (called the work function) Kinetic Energy Photoelectric Effect: Einstein’s Photoelectric Law