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Interference

Interference. Thomas Young. Isaac N ewton did not believe that Light could be a wave, but later a Physicist called Thomas young showed that light travels in waves. In fact, the interference and diffraction of light cannot be explained any other way. What is Interference?.

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Interference

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  1. Interference

  2. Thomas Young Isaac Newton did not believe that Light could be a wave, but later a Physicist called Thomas young showed that light travels in waves. In fact, the interference and diffraction of light cannot be explained any other way

  3. What is Interference? Interference is adding two waves are superposed are in the same place at the same time

  4. What is Interference? • The resultant displacement at any point is found by adding the displacement of each separate wave .

  5. Constructive Interference Adding to waves that are in phase For example, if the crests (or troughs) of two light waves are coincident, they combine together to create an amplified wave in what is known as constructive interference.

  6. Distractive Interference Adding two waves that are in anti-phase In the opposite scenario, where the crests of one wave are aligned with the troughs of another, they cancel each other out and the light disappears. This is destructive interference.

  7. Guitar Strings

  8. Guitar Strings A combination wave composed of the 1st harmonic and the third harmonic.

  9. Standing Waves The term standing wave is often applied to a resonant mode of an extended vibrating object. The resonance is created by constructive interference of two waves which travel in opposite directions in the medium, but the visual effect is that of an entire system moving in simple harmonic motion. The sketches illustrate the fundamental and second harmonic standing waves for a stretched string.

  10. Standing Waves

  11. Standing Waves

  12. Adding reflected waves

  13. Nodes and Antinodes This diagram shows what the string is doing : At the Nodes, the string does not move at all, and you can see the string quite distinctly. At the Anti Nodes the string oscillates with maximum amplitude, and so it appears as blur. Between the nodes and anti nodes, the string would oscillate, but with less amplitude than at the anti nodes. The appearance is of a set of blurry loops. These are called stationary waves, or standing waves, Because the pattern does not move along the string

  14. Vibrating String The fundamental vibrational mode of a stretched string is such that the wavelength is twice the length of the string. Applying the basic wave relationship gives an expression for the fundamental frequency: can be put in the form: Since the wave velocity is given by , the frequency expression can be put in the form:

  15. Asmaa’ Khaled Ola Mohammed Alaa’ Sharaf 11/A

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