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How to Calculate the Diffraction Angle for Multiple Slits

Published in Wave Diffraction Calculation 3 mins read

Calculating the effects of wave diffraction often involves determining the angles at which bright and dark spots appear in the resulting pattern. For the specific case of diffraction through multiple slits, there is a calculation method to determine the diffraction angle.

Calculation Method

According to the provided information, to calculate the diffraction angle for multiple slits, you need to perform the following steps:

  1. Multiply the number of slits by the wavelength of the wave.
  2. Divide the result by the distance between the slits.
  3. Take the inverse sine (arcsin) of the final result.

This method can be summarized by the formula:

Diffraction Angle = arcsin((Number of slits × Wavelength) / Distance between slits)

Step-by-Step Calculation

Follow these steps to calculate the diffraction angle:

  1. Multiply: Get the value for the number of slits and multiply it by the wavelength of the wave (λ).
  2. Divide: Take the product from Step 1 and divide it by the distance between the slits (d).
  3. Inverse Sine: Use a calculator to find the inverse sine (sin⁻¹ or arcsin) of the value obtained in Step 2. This will give you the diffraction angle (θ).

Key Variables

Understanding the variables involved is crucial:

  • Number of slits: The total count of narrow openings the wave passes through.
  • Wavelength (λ): The distance between successive crests or troughs of the wave.
  • Distance between slits (d): The measurement from the center of one slit to the center of the adjacent slit.
  • Diffraction Angle (θ): The calculated angle, typically measured from the original direction of the wave propagation to a specific point in the diffraction pattern.

Example Calculation

Let's illustrate with a hypothetical example:

Suppose you have:

  • Number of slits = 5
  • Wavelength (λ) = 600 nanometers (nm), which is 600 x 10⁻⁹ meters
  • Distance between slits (d) = 0.01 millimeters (mm), which is 0.01 x 10⁻³ meters

Now, apply the steps:

  1. Multiply Number of slits by Wavelength: 5 × (600 x 10⁻⁹ m) = 3000 x 10⁻⁹ m = 3 x 10⁻⁶ m
  2. Divide by Distance between slits: (3 x 10⁻⁶ m) / (0.01 x 10⁻³ m) = (3 x 10⁻⁶) / (1 x 10⁻⁵) = 0.3
  3. Take the inverse sine: arcsin(0.3)

Using a calculator, arcsin(0.3) is approximately 17.46 degrees.

What This Angle Represents

The angle calculated using this method represents a specific angle within the diffraction pattern formed by the waves passing through the multiple slits. This angle is typically measured relative to the central maximum (the brightest spot) of the pattern.

By following these steps and using the specified variables, you can calculate this particular diffraction angle according to the described method.

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