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 π‘›πœ† where n = 0, 1, 2,…

  • Dark bands correspond to path differences of (𝑛 + 1/2)πœ†

  • 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 π‘ π‘–π‘›πœƒ = π‘›πœ†

For destructive: 𝑑 π‘ π‘–π‘›πœƒ = (𝑛 + 1/2)πœ†