Physical science quarter 2 Nature-of-Light.pptx

for educational purpose only

1. Nature of Light LESSON 1WEEK 3

2. 1. What is the path of the light that you have observed in prism? 2. Do you think it has particles? Did it behave as a wave just like what happens in water? 3. what happen to the light in mirror? 4. what happen to the light in lens? 5. what happen to the light in rough surface? Observe a flashlight. Switch it on and draw the path of the light you see from the flashlight. answer the guide questions below.

3. The Corpuscles theory or Particle theory was suggested by Sir Isaac Newton . Sir Isaac Newton's prism experiments was a proof that light traveled as a shower of particles, each proceeding in a straight line until it was refracted, absorbed, reflected, diffracted or disturbed in some other manner. Particle Theory or Corpuscles Theory

4. A number of scientists in the early 1700s did not agree with his corpuscular theory. They have argued that if light consisted of particles, then when two beams are crossed, some of the particles would collide and cancel each other. Christian Huygens , a dutch physicist, suggested that light waves traveled through space. Wave Theory

5. Light’s Energy LESSON 2

6. In the previous lesson you have learned about corpuscle theory and wave theory. Corpuscle theory describes light as a particle and wave theory described the tendency of light to behave like wave. Light is an electromagnetic wave. It has a frequency of 4 x10^14Hz to 7.90 x10^12 Hz. The wavelength of light ranges from 380nm to 750nm

7. Find the words on the Word search puzzle

8. Photon Light can be described as a particle (photon) or a wave (electromagnetic wave). The electromagnetic wave can be pictured as oscillating electric and magnetic fields that move in a straight line at a constant velocity (the speed of light). Photon is defined as a discrete bundle of electromagnetic energy moving at the speed of light, has no rest mass but has momentum, and carries energy. how we see colors with our naked eye?

9. The composition of atoms are electrons, protons and neutrons. In an atom, electrons are located at specific energy levels. A given certain amount of energy, electrons can move from lower energy level to higher energy level. Photon theory of light states that photon is composed of electromagnetic energy . This energy may be given to an electron during collision and causes the movement of the electron to a higher energy level. Photon Theory

10. Photoelectric effect was proposed by Albert Einstein in 1905. Photoelectric effect refers to a photon incident to a metal surface and transfer all its energy to the electron. For each frequency or color of the incident light, each photon carried energy. Increasing incident of photons means increasing the intensity of light and energy of the photons remained the same. This means that increasing the incident photons, more electrons are ejected. Photoelectric effect

11. Colors are not natural to objects. The colors of the objects appear due to the light they emit. Colors are determined by the frequencies. Colors are only perceived by the human brain. When the light reaches the eye, the receptor cell of the eye or retina, gives signal to the brain, which interprets the image with colors. As the frequency increases, the color gradually changes from red to violet. Color Spectra

12. Photons of different colors have different energies. Red light has low frequency and long wavelength, this means that red light has low energy. On the other hand, blue has a higher frequency and shorter wavelength, which means it has more energy. Ultraviolet light is beyond the visible light, this means it has higher frequency and shorter wavelength. This explains why we get easily sunburned when exposed under ultraviolet rays of light Ultraviolet radiation

13. Electron’s Wave Property & Physical Optics LESSON 1 WEEK 4

14. The quantum theory was proposed by Max Planck in 1900. Quantum theory describes that light emits energy in discrete packets called quantum (pl. Quanta). Upon the proposal of this theory other scientists gained interest on the study of the electrons wave-like proper Electron’s Wave Property

15. Look at the timeline below to see the contributions of different scientist on the idea that electrons also behave like waves just

16. From the result of Broglie’s hypothesis and Heisenberg Uncertainty principle , Erwin Schrödinger formulated a model of an atom that assumed the electrons could be treated at matter waves . He derived equations called wave functions . The wave functions that are derived from Schrödinger's equation for a specific atom are also called atomic orbitals . The square of a wave function is proportional to the probability of finding an electron in a particular volume of space within an atom. The greatest probabilty of finding an electron in an orbital is in the densest ares , similarly, the lowest probabilty of finding an electron in the orbital of least dense.

17. Search on Davisson- Germer Experiment. Make a synthesis of their experiment Write your answer in short or A4 coupon Submit your kaleidoscope tomorrow.

18. Physical Optics Lesson 2

19. In the previous lesson, you have learned that light can be absorbed, transmitted, bent, bounce, dispersed or scattered when it encounters matter. You also have learned that light’s reflection and refraction is explained by considering light as a particle and as a wave, this is a branch of optics called GEOMETRIC OPTICS . In this lesson, you will learn about the other branch of optics which is the physical optics . This includes, dispersion, scattering, interference and diffraction

20. Prism is a material made from glass or any transparent usually with a triangular shape. Visible light is capable of passing through prism. When light passes through prism, the light separates into its component color, it is called dispersion. Newton was the first to observe dispersion of a white light. Rainbow is an example of dispersion of light. The water droplets act as the prism. The water droplet disperses the color. Dispersion

21. Scattering is the phenomenon wherein light has the capability to be redirected. The particles responsible for this phenomenon is called scaterers . Scattering of light is the reason why we see blue skies and red-orange sunrise and sunset. The dust particles and atoms of oxygen and nitrogen in the atmosphere act as a scatterer that scatters sunlight in all direction. Scattering of Light

22. Violet is the light that is most scattered, it is follwed by indigo , blue , green , yellow , orange and red . The shorter the wavelength of the light the more it is scattered . Our eyes is not sensitive with the violet and indigo light. Blue is the most predominant in our sight and this is the reason why we see a blue sky. During sunrise and sunset, the sunlight travels farther, blue light have been scattered, this leaves only yellow, orange and red to be scattered. It is the reason for a red-orange skies during sunrise and sunset.

23. Water droplets and ice crystals may also act as a scatterer . This is a reason why clouds are seen as white. When clouds are heavier and thicker, water droplets become less effective scatterer , so they become absorbers. This is a result of a darker appearance of clouds.

24. Interference is the combination of waves traveling in the same medium at the same time. Waves follow the principle of superposition, which means waves can combine constructively or destructively Interference

25. Constructive interference, waves reinforce each other while destructive interference waves cancel each other. This happens if two coherent light passes through narrow slits, a series of bright and dark fringes may appear to the screen. When you see bright fringes on the screen, this means the light waves have constructive interference. When you see dark fringes on the screen, it is destructive interference.

26. Diffraction is the bending of light as it passes through an opening or an obstacle . The obstacle may be a slit, wire, hole, strands of hair, feather and the like. When you try to observe closely, you may observe shadows are bordered by alternating dark and bright infringes. Try doing it using your two fingers close with each other and try to peep between them . Diffraction