WAVE-PARTICLE DUALITY In 1905, a German physicist named Albert Einstein developed a novel theory about electromagnetic (EM) radiation which is called the wave-particle duality theory. It explains the behavior of electromagnetic radiation as a wave and a particle. Einstein explained that when an electron returns to a lower energy level and gives off alactromagnatic energy, the energy is emitted as a discrete "packet" of energy. This packet of energy is called photon. According to Einstein, a photon is in a form of particle but moves like a wave (see Figure 1). The theory suggests that waves of photons traveling through matter of space make up electromagnetic radiation. Energy of a Photon * the pacion lower energy love and Photon energy is the energy carried by releases a discrete a photon. The photon energy is directly proportional to its electromagnetic frequency and thus, inversely proportional to the wavelength, the higher amount of photon's frequency, the higher its energy and the longer the wavelength of the photons, the lower its energy. There are different units that can be used in photon energy, these are electronvolt (@V) and Source: Wave-Faride Theory. https:/flexbooks.ck12.org/cbook/ck-12- physics-Texbook-2.0/section:13.4 primary/lesson/wave-particle-theory-ms-ps the joule. One joule is equivalent to 6.24 x 1018 eV, the large units can be used for representing the energy of Figure 1. Wave of photon travelling through matter or space photons with higher frequency and higher energy like gamma rays, as contrasting to photons with low energy photons, like those in the radio frequency region of the electromagnetic spectrum. Evidence for the Wave -Particle Theory Evidences were discovered and showed after Einstein proposed his wave-. particle duality theory. Scientists shone laser light using two slits in a barrier that blocked the light (see Figure 2). They took photos of the light that passed through the slits using a very sensitive camera. The photos showed small pinpoints of light passing through the double slits. This seemed to reveal that light consists of very small particles. However, when the camera was exposed to the light for a long time, the pinpoints accrued in bands that look like Source: Wave-Particle Theory, https./lexbooks.ck12.org/cbookick-12-physics- flexbook-2.0 section/13.4/primary lesson/wave-partide-theory-ms-ps interfering waves . Therefore, the experiment exhibited that light appears to Figure 2. Experiment showing that light is both a particle and consist of particles that act like waves. wave ston SAD BOYDirections: The concepts below are connected to your explanation in the Light Mystery Activity. Let us deepen your understanding by explaining the phenomena being exhibited by the picture below. LIGHT BEAM REFLECTED RAY AIR WATER REFRACTED Photocredit: Peralta, Rommel Carl (2020). Physical Science Module Figure 3: Light Ray Diagram Guide Questions: 1. How is light propagated? 2. What two important aspects of propagation of light are being exhibited by Figure 3? When a light wave strikes a smooth interface separating two transparent materials (such as air, glass or water), the light wave is somewhat reflected and partly refracted into the second medium or material, as shown in Figure 3. For example, when you look into a glass window in the mall from the street, you see a reflection of the street scene, but a person inside the mall can look out through the glass window at the same scene as light reaches him or her by refraction. Now, try to describe REFLECTION and REFRACTION of light by illustrating the particle and wave model of light. Describe how light is being propagated in each model. 6Particle and Wave Refraction amen a light beam travels between two media having different refractive indices, the ght beam undergo refraction, and changes its direction when passes through differhe Refraction of Particles and Waves medium (see Figure 3 & 4) just like in Force Pulls picture B which shows that the light was Particles Waves Wave Edge bended when it passes through a glass of into Medium Bends at . Particles Entry water. On the other hand, a model for each can be devised to explain and to determine whether the light beam is composed of waves or particles, phenomenon (see Figure 4). Huygens' wave theory explains Wave Edge that a small portion of each angle Bends at Exit wavefront should hit the second medium Opposite Force before the rest of the front reaches the Pulls Particles From Medium interface. Light beam will start to move through the second medium while the other Figure 4. Refraction of Particles and Waves part of the wave is still traveling in the first medium, but will move slower due to the higher refractive index of the second medium. The light beam will bend into the second medium since the wavefront is traveling at two different speeds, therefore changing its angle of propagation. Particle and Wave Reflection Wave theory speculates that a Particles and Waves Reflected by a Mirror source of light releases light waves that spread in various directions. The light waves are reflected according to the arrival angles when the light beam touches a mirror, but with each wave turned back to front that yielded a reversed image (Figure 3). The shape of arriving waves depends upon the distance Particles Waves of the light source from the mirror. Light that came from a close source maintains Figure 5. Particles and Waves Reflected by a Mirror a spherical, highly curved wavefront. On the other hand, the light beam being emitted from a distance source will spread more and impact the mirror with wavefronts that are almost planar. In the case for a particle nature of light, light emitted by a source, regardless of the distance, light arrives at the mirror surface as a stream of particles, which bounce away or are reflected from the smooth surface (see Figure 5). Since the particles are very small, a great number of particles are involved in a propagating light beam. Upon touching the mirror, the particles bounce from various points, so their order in the light beam is reversed upon reflection to produce a reversed image. Both the particle and wave theories explain reflection from a smooth surface. However, the particle thenry also suggests that if light heam touches a very rough surface, its particles bounce away at different angles which resulted to the scattering the light. SOURCE & PHOTOCREDITS: Robert T. Sutter, Matthew J. Parry-Hill and Michael W. Davidson Accessed October 19, 2020. https://micro.magnet.fsu.edu/primer/java/particleorwave/refraction/index.htmlDirections: Look around inside your house, REINFORCEMENT take a picture exhibiting the materials, phenomena and scenarios where you can observe reflection and refraction of light. Make an inference about how light is being propagated using wave and particle theory