PHOTON THEORY OF LIGHT

light

1. Photon theory of light

2. Objectives: Relate the atomic spectra to the photon theory of light Describe the relationship between the energy of the photon and its frequency Explain certain phenomena using the photon theory Apply speed- wavelength- frequency relationship in problem solving Describe the attempts of Galileo and Roemer to measure the speed of light

3. Speed of light Galileo Galilei One of the scientists who tried to measure the speed of light Believed that light have speed Designed an experiment to measure the speed of light

4. Ole roemer Danish astronomer who also attempted to measure the speed of light Very keen in observing Io (Jupiter’s moon) Was been observed of having a black shadow or eclipse casted by it Makes a complete orbit around Jupiter for 1.76 days (or 1 day,18 hours, and 14 minutes)

5. Electromagnetic spectrum NOTE: All electromagnetic waves travel in a vacuum at a constant speed of 3x m ⁄s  

6. Light as a particle Isaac Newton Noticed that light casted sharp shadows He thought of light as something like matter Formulated the particle theory of light Particle Theory Visible light is composed of submicroscopic particles called photons Photons These are elementary paticles of light that have properties of a wave .

7. Some Properties of photons They move at a constant speed of 3 x They are massless They carry energy and momentum They have no charge like a neutron  

8. *particle theory of newton cannot explain the light interference Light interference Light sources of the same color overlapped light source of different color overlapped with two sources of the same color The interaction of correlated or coherent waves which are of the same frequencies or of different frequencies Light become more intense or brighter New color was produced

9. Albert Einstein Revive the theory of light interference Introduced the photoelectric effect Electrons are emitted from a metallic surface when subjected to an incident light consisting of photons

10. Atomic spectrum Is the spectrum of frequencies of electromagnetic radiation emitted or absorbed during the transition of electrons between energy levels within an atom Electrons that have absorbed energy jump to a higher energy level and are said to be in an excited state.