Now, select the Slits simulation at the bottom of the screen, and Light (red) for the type of wave, as before. Also, make sure there is a barrier with one slit, and use the tape measure as well as the slider bar below the slit to place it roughly 1290 nm away from the light source. Adjust the slit width to 300 nm. Finally, select the start button at the source location to begin producing the waves.

see that the central maximum is very high and wide, with some lines of interference on the sides whose intensity decreases very quickly, this is because the cover one of the slits the pattern changes to the diffraction pattern of a slit.

Explanation:

In this case when the pattern occurs we see that the central maximum is very high and wide, with some lines of interference on the sides whose intensity decreases very quickly, this is because the cover one of the slits the pattern changes to the diffraction pattern of a slit.

               I = I₀  sin β/2  /(β/2)

Where β/2 is the angle measured from the slit

When you change the cardboard to the other slit the pattern is the same, but centered of the slit through which the light passes.

By uncovering the two slits these patterns are added by giving the known double slit interference pattern, many interference lines with a slow change in intensity