Huygen’s principle, Superposition & Interference of waves, and Young’s experiments.
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This presentation by Mainul Hossan covers key concepts in optics, including Huygen's principle, superposition, and interference of waves, as well as Young's two-slit experiment. Huygen's principle states that every point on a wavefront acts as a source for spherical wavelets, which can explain refraction and interference phenomena. The presentation highlights that interference patterns arise from the overlapping of waves, leading to constructive and destructive interference, as demonstrated in Young's experiment.
Huygen’s principle, Superposition & Interference of waves, and Young’s experiments.
- 1. Presented By Mainul Hossan Roll: 2450 Department of Physics, Jahangirnagar university. Course Name: OPTICS Course Code: PH-202 Course Instructor: Asst. Prof. Shariful Islam WELCOME TO MY PRESENTATION
- 2. OUTLINE OF THE PRESENTATION 1)Huygen’s principle. 2)Superposition & Interference of waves 3)Young’s experiments.
- 3. Huygen’s principle Christiaan Huygens A seventeenth-century Dutch mathematician and scientist (physicist, astronomer, probabilist, horologist). In 1678, Huygens proposed that every point on the wave front of a wave was a source of a spherical wave. The resultant wave is determined by adding all the waves from the point sources.
- 4. Huygen’s Principle states that each and every point on a wavefront serves as a source of wavelets which then spread forward at the same speed. The new wavefront is in a line tangent to all of the wavelets.
- 5. USES OF HUYGEN’S PRINCIPLE 1. It can be used to explain the phenomenon of refraction and interference. 2. It helps in explaining the linear and spherical wave propagation. LIMITATIONS OF HUYGEN’S PRINCIPLE 1. It is a consequence of the homogeneity of space (the space is said to be uniform in all the locations). 2. It was noticed by Jacques Hadamard in 1900, that Huygen’s principle could not be applied when the number of spatial dimensions was equal
- 6. Superposition and Interference If two waves occupy the same space, their amplitudes add at each point. They may interfere either constructively or destructively.
- 7. Superposition and Interference Interference is only noticeable if the light sources are monochromatic (so all the light has the same wavelength) and coherent (different sources maintain the same phase relationship over space and time). If this is true, interference will be constructive where the two waves are in phase, and destructive where they are out of phase.
- 8. Superposition and Interference In this illustration, interference will be constructive where the path lengths differ by an integral number of wavelengths, and destructive where they differ by a half-odd integral number of wavelengths.
- 9. Superposition and Interference To summarize, the two path lengths l1 and l2 will interfere constructively or destructively according to the following:
- 10. Young’s Two-Slit Experiment In this experiment, the original light source need not be coherent; it becomes so after passing through the very narrow slits.
- 11. Young’s Two-Slit Experiment If light consists of particles, the final screen should show two thin stripes, one corresponding to each slit. However, if light is a wave, each slit serves as a new source of “wavelets,” as shown, and the final screen will show the effects of interference. This is called Huygens’s principle.
- 12. Young’s Two-Slit Experiment As the pattern on the screen shows, the light on the screen has alternating light and dark fringes, corresponding to constructive and destructive interference. The path difference is given by: Therefore, the condition for bright fringes (constructive interference) is:
- 13. Young’s Two-Slit Experiment The dark fringes are between the bright fringes; the condition for dark fringes is:
- 14. Young’s Two-Slit Experiment This diagram illustrates the numbering of the fringes.
- 15. Any query?