The Young Two Slit Interference model simulates the interference pattern of light as it travels through two slits to a screen. This result was first described by Young who used the wave theory of light to describe the interference of light through two slits. The interference pattern is due to the difference in path length of the light from each slit as it travels to the screen. When this path length difference is an integral number of wavelengths, constructive intereference results; when this path length difference is a half integer number of wavelengths, destructive interference results. The intensity of the light that reaches the screen is related to the wavelength of light, the slit separation, and the angle away from the center of the screen. In the simulation one can change the wavelength, the slit separation, and whether the pattern is shown on a screen or on a photographic plate.

Young Two Slit Interference model was created using the Easy Java Simulations (EJS) modeling tool.  It is distributed as a ready-to-run (compiled) Java archive.  Double clicking the ejs_young_english.jar file will run the program if Java is installed.

Please note that this resource requires at least version 1.5 of Java (JRE).