Young's double-slit experiment is a classic experiment in physics that demonstrates the wave-like nature of light. It was first performed by Thomas Young in the early 19th century and has since become a fundamental experiment in the field of optics.
In the double-slit experiment, a beam of light passes through a barrier with two closely spaced slits, creating two separate sources of light waves. These waves then interfere with each other as they propagate and overlap on a screen placed behind the slits. The resulting pattern on the screen consists of a series of bright and dark fringes, known as interference fringes.
The reason monochromatic light is used in Young's double-slit experiment is to ensure that the waves are in phase and have a well-defined wavelength. Monochromatic light consists of a single wavelength, meaning that all the waves emitted from the two slits have the same frequency. This is crucial for the interference pattern to be observed.
When two waves of the same frequency overlap, they can either interfere constructively, where the peaks of one wave align with the peaks of the other, resulting in a bright fringe, or interfere destructively, where the peaks of one wave align with the troughs of the other, resulting in a dark fringe. This interference pattern arises due to the superposition of the waves.
If light with multiple wavelengths or a broad spectrum were used in the experiment, the interference pattern would become blurred or distorted. This is because waves of different wavelengths have different phase relationships and do not produce a well-defined interference pattern. Monochromatic light ensures that the interference pattern is clear and distinct, allowing for accurate observations and measurements in the double-slit experiment.