1. The Photoelectric Effect 6 th Grade Physical Science 6 th Grade Physical Science Mrs. Nadine Uremovich

2. Photoelectric Photo-electric effect Photo-electric effect Takes solar energy and converts it to electrical energy Takes solar energy and converts it to electrical energy Remember energy cannot be created or destroyed---only changed/converted Remember energy cannot be created or destroyed---only changed/converted

3. Early Ideas About Light In 1905, most scientists believed that light was a wave (like a wave on the ocean). In 1905, most scientists believed that light was a wave (like a wave on the ocean). A few scientists thought that light was a stream of particles (like falling rain). A few scientists thought that light was a stream of particles (like falling rain). http://ocean.nationalgeographic.com/ocean/photos/ocean-for-life/#/open-water- ofl_39512_600x450.jpg http://www.abstractinfluence.com/forums/gallery/image_page.php?album_id=23 &image_id=8237

4. Rain and Waves! http://d1068036.site.myhosting.com/ePhysics.f/labIV_13.html http://d1068036.site.myhosting.com/ePhysics.f/labIV_13.html Albert Einstein said that light acted like both a wave and a particle.

5. Max Planck Max Planck discovered that certain types of metal would release electrons when light hit it. Max Planck discovered that certain types of metal would release electrons when light hit it. He did a math trick to explain the phenomena He did a math trick to explain the phenomena His math trick put waves of light into packets (particles) although he didn’t want to say that light was particles. His math trick put waves of light into packets (particles) although he didn’t want to say that light was particles. Einstein thought Planck’s equations did explain light’s particle nature. Einstein thought Planck’s equations did explain light’s particle nature. http://en.wikipedia.org/wiki/Max_Planck

6. Wave-Particle Duality Today it is accepted that light has a wave nature and a particle nature. This is called wave-particle duality Today it is accepted that light has a wave nature and a particle nature. This is called wave-particle duality It means that light travels through space as a wave and interacts with matter as a particle It means that light travels through space as a wave and interacts with matter as a particle

7. The Photoelectric Effect The photo electric effect is at work in many devices today The photo electric effect is at work in many devices today Solar batteries (calculators) Solar batteries (calculators) Automatic door openers at the grocery store Automatic door openers at the grocery store Lasers Lasers CD & DVD players CD & DVD players The safety mechanism on your garage door The safety mechanism on your garage door

8. Photo-electric effect With these devices, light is converted to electricity. With these devices, light is converted to electricity. The solar calculator converts solar energy into electrical energy The solar calculator converts solar energy into electrical energy Beams of light are part of the electrical circuit for mechanisms that open and close doors automatically Beams of light are part of the electrical circuit for mechanisms that open and close doors automatically Lasers in CDs, DVDs, and UPC scanners use photoelectric technology. Lasers in CDs, DVDs, and UPC scanners use photoelectric technology.

9. Explore a photoelectric device Test a solar calculator Test a solar calculator Find out if the type of light makes a difference in power Find out if the type of light makes a difference in power Classroom light Classroom light Sunlight Sunlight Find out how much of the solar cell you can cover up and have enough power to effectively use the device Find out how much of the solar cell you can cover up and have enough power to effectively use the device