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🔋college physics i – introduction review

Constructive interference for a double slit

Written by the Fiveable Content Team • Last updated September 2025
Written by the Fiveable Content Team • Last updated September 2025

Definition

Constructive interference occurs when two or more waves superpose to form a wave with a larger amplitude. In a double slit experiment, this happens when the path difference between the two waves is an integer multiple of the wavelength.

5 Must Know Facts For Your Next Test

  1. Constructive interference results in bright fringes on the screen in a double slit experiment.
  2. The condition for constructive interference is given by $d \sin(\theta) = m\lambda$, where $d$ is the slit separation, $\theta$ is the angle of diffraction, $m$ is the order of the fringe, and $\lambda$ is the wavelength of light.
  3. Constructive interference produces maxima at points where waves from both slits are in phase.
  4. The central maximum (m=0) is always located at the midpoint directly opposite to the slits.
  5. Higher-order maxima ($m = \pm1, \pm2, ...$) are symmetrically distributed on either side of the central maximum.

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