Properties of Waves - Part B

Properties of Waves

• Phase of a Wave: Refers to the position of a point in a wave cycle at any instant of time from mean position. It is crucial to understand phase differences between multiple waves rather than their absolute phase values.

  

• Reflection of Waves: All types of waves (light, sound, water) experience reflection when they encounter a boundary. Reflection is defined as the change in direction of wave propagation when meeting a boundary where properties are:

  

  • Law of Reflection states:

  • Angle of incidence = Angle of reflection.

• Properties of Reflection:

  

• Image Formation via Reflection:

Images formed by a plane mirror have specific properties:

• Superposition of Waves: When two or more waves of the same type cross paths in the same medium:

  • Constructive Interference: Occurs when waves are in phase. Resultant amplitude = sum of individual amplitudes.

  • Destructive Interference: Occurs when one wave’s crest meets another’s trough. Resultant amplitude = difference of individual amplitudes.

  • Shows where regions of high and zero amplitude occur.

• Interference: Superposition of two waves of same frequency & amplitude travelling in the same direction when produced by two coherent sources.

  

• Conditions for Interference:

  

• Interference with Light: When monochromatic light passes through two slits:

  • Bright regions (constructive interference) and dark regions (destructive interference) are produced.

  • Bright bands correspond to path differences of 𝑛𝜆 where n = 0, 1, 2,…

• Dark bands correspond to path differences of (𝑛 + 1/2)𝜆

  

• Calculating Path Differences: When two waves travel different distances.

  • Use sine functions in small angle approximations for calculations based on the distance and angle involved.

  • For constructive: 𝑑 𝑠𝑖𝑛𝜃 = 𝑛𝜆

For destructive: 𝑑 𝑠𝑖𝑛𝜃 = (𝑛 + 1/2)𝜆