Chapter 8 Physics Class 11 Notes

• Important from chapter 8 physics class 11 important questions Punjab Textbook.
• Progressive waves
• Transverse and longitudinal waves
• transverse periodic waves
• periodic waves
• Important from chapter 8 physics class 11 numericals Punjab Textbook.
• phase relationship between two points on a wave
• longitudinal periodic waves
• the speed of sound in air
• Effect of variation of pressure, density, and temperature on the speed of sound in a gas.
• Important from chapter 8 physics class 11 exercise solutions Punjab Textbook.
• Principle of superposition: So far, we have considered single waves. What happens when two waves encounter each other in the same medium? Suppose two waves approach each other on a coil of spring, one travelling towards the right and the other travelling towards left. Fig. 8.7 shows what you would see happening on the spring. The waves pass through each other without being modified. After the encounter, each wave shape looks just as it did before and is travelling along just as it was before.
• This phenomenon of passing through each other unchanged can be observed with all types of waves. You can easily see that if is true for surface ripples.
• But what is going on during the time when the two waves overlap? Fig. 8.7 (c) shows that the displacernents they produce just add up. At each instant, the spring's displacement at any point in the overlap region is just the sum of the displacements that would be caused by each of the two waves separately.
• Thus, if a particle of a medium is simultaneously acted upon by n waves such that its displacement due to each of the individual n waves be yi y then the resultant displacement of the particle, under the simultaneous action of these in waves is the algebraic sum of all the displacements interference.
• Beats
• Reflection of waves
• stationary waves
• Important from chapter 8 physics class 11 short questions Punjab Textbook.
• stationary waves in a stretched string: Consider a string of length/ which is kept stretched by clamping its ends so that the tension in the string is F. If the string is plucked at its middle point, two transverse waves will originate from this point. One of them will move towards the left end of the string and the other towards the right end. When these waves reach the two clamped ends, they are reflected back thus giving rise to stationary waves. As the two ends of the string are clamped, no motion will take place there. So nodes will be formed at the two ends and one mode of vibration of the string will be as shown in Fig. 8.13 with the two ends as nodes with one antinode in between. Visually the string seems to vibrate in one loop. As the distance between two consecutive nodes is one half of the wavelength of the waves set up in the string, so in this mode of vibration, the length / of the string.
• Stationary waves in air columns
• Important from chapter 8 physics class 11 exercise Punjab Textbook.
• Doppler effect: An important phenomenon observed in waves is the Doppler effect. This effect shows that if there is some relative motion between the source of waves and the observer, an apparent change in frequency of the waves is observed.
• This effect was observed by Johann Doppler while he was observing the frequency of light emitted from distant stars. In some cases, the frequency of light emitted from a star was found to be slightly different from that emitted from a similar source on the Earth. He found that the change.
• Applications of the Doppler Effect
• Important from chapter 8 physics class 11 conceptual questions Punjab Textbook.

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