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# Chapter 9 Notes | Physics 1st Year

## “Work and Energy”

#### Index:

1. Optics
2. Wavefronts
3. Huygen’s Principle
4. Interference of Light Waves
5. Young’s Double Slit Experiment
6. Interference in thin films
7. Newton’s Rings
8. Michelson Interferometer
9. Diffraction of Light
10. Diffraction due to Narrow Slit
11. Diffraction Grating
12. Diffraction of X-Rays by crystals
13. Difference b/w Interference and Diffraction
14. Polarization

#### Key Points:

1. A surface passing through all the points undergoing a similar disturbance (i.e. having the same phase.) at a given instant is called wave-front
2. When the disturbance is propagated out in all directions from a point source , the waveform in this case are spherical.
3. Radial lines leaving the point source in all directions represent rays.
4. The distance between two consecutive waveform is called wavelength.
5. Huygens principle states that all points on a primary wave-front can be consider as the source of secondary wavelets.
6. When two or more waves overlap each other, there is resultant waves, This phenomenon is called interference.
7. Constructive interference occurs when two waves, travelling in the same direction overlap and the amplitude of the resultant wave is greater than either of the individual waves.
8. In case of destructive interference , the amplitude of the resulting waves is less than either of the individual waves.
9. Newton’s rings are circular fingers formed due to interference in a thin air film enclosed between a convex lens and a flash glass plate.
10. Michelson’s interference is used for very precise length measurements. the distance l of the moving mirror when m fringe move in view is mλ/2.
11. Polarization of light proves that light consists of transverse electromagnetic waves

Categories: Fsc Part 1,Notes,Physics

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