What does shifting the phase between the sources in a double slit experiment do to the interference pattern?
In a double slit experiment, shifting the phase between the sources can affect the interference pattern by modifying the relative positions of the bright and dark fringes.
When light passes through the two slits, it creates overlapping wavefronts that interfere with each other, resulting in an interference pattern on a screen placed behind the slits. The interference pattern is caused by the constructive and destructive interference of the light waves from the two slits.
When the phase difference between the waves from the two slits is constant, the interference pattern remains the same. However, when the phase difference varies, the interference pattern can change significantly.
To understand this, you need to know about the concept of phase difference. In simple terms, the phase indicates the position of a wave relative to a reference point. It is measured in degrees or radians.
When the phase difference between the waves from the two slits is zero (or a multiple of 2π), the crests and troughs of the waves coincide, resulting in constructive interference. This leads to bright fringes in the interference pattern.
On the other hand, when the phase difference between the waves is a half-wavelength (or an odd multiple of half-wavelengths), the crests of one wave overlap with the troughs of the other, leading to destructive interference. This results in dark fringes in the interference pattern.
Now, shifting the phase between the sources means altering the phase difference between the waves from the two slits. This can be achieved by introducing a phase shift (usually done by adjusting the path length of one of the waves).
By changing the phase difference, you can modify the positions of the bright and dark fringes in the interference pattern. For instance, if you introduce a half-wavelength phase shift, the dark fringes will shift to the positions where the bright fringes originally were, and vice versa.
In summary, shifting the phase between the sources in a double slit experiment can affect the interference pattern by altering the relative positions of the bright and dark fringes.