Interference Physics Example 3

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Example 3

medium
Two coherent light sources create an interference pattern. The third bright fringe is observed at an angle where the path difference is 3λ3\lambda. If λ=600 nm\lambda = 600 \text{ nm}, what is the path difference in meters?

Solution

  1. 1
    Constructive interference occurs when path difference =mλ= m\lambda for integer mm.
  2. 2
    For the third bright fringe (m=3m = 3): Δ=3λ=3×600×10−9=1.8×10−6 m\Delta = 3\lambda = 3 \times 600 \times 10^{-9} = 1.8 \times 10^{-6} \text{ m}

Answer

Δ=1.8×10−6 m=1.8 μm\Delta = 1.8 \times 10^{-6} \text{ m} = 1.8 \text{ } \mu\text{m}
Bright fringes in an interference pattern correspond to constructive interference where the path difference is a whole number of wavelengths. Each successive fringe adds one more wavelength of path difference.

About Interference

The phenomenon that occurs when two or more waves overlap in space, combining their displacements at every point according to the principle of superposition.

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More Interference Examples

Example 1 easy

Two speakers emit identical sound waves in phase. A listener stands equidistant from both speakers.

Example 2 medium

In a double-slit experiment, light of wavelength [formula] passes through slits [formula] apart. A s

Example 4 hard

In a double-slit experiment, the slit separation is [formula] and the screen is [formula] away. If t

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