1. Module 6

1.10. Page 4

Lesson 2

Module 6—Wave-Particle Duality and Quantum Physics

 

Reflect and Connect

 

An image shows three spotlights shining through a cloud of smoke. Are these lights releasing particles or waves or both?

© Krkr/shutterstock

Is light a wave? Is it a particle? Is it both?

 

The photoelectric effect supports the notion of wave-particle duality for electromagnetic radiation. The classical wave theory based on Maxwell’s electromagnetic waves was unable to explain several characteristics of the photoelectric effect. The instant release of photoelectrons when the EMR is incident on the metal meant that classical waves were not being continually absorbed until enough energy had accumulated to eject a photoelectron. The energy must be absorbed in bundles, or photons (light quanta), suggesting a particle nature for the incident EMR. There was also no clear relationship between the brightness, or intensity, of the EMR and the kinetic energy of the released photoelectrons. Again, this is understood by limiting the energy of each photon to a specific value, or light quanta.

 

The idea of light quanta (photons) treated EMR as a particle, which helped scientists understand the photoelectric effect. In combination with the wave-like characteristics of EMR from other experiments, the notion of wave and particle characteristics took on more meaning and, in doing so, promoted the notion of wave-particle duality.

 

Module 6: Lesson 2 Assignment

 

Remember to submit the Module 6: Lesson 2 Assignment to your teacher.