Interference with synchronous sources

There are from 1 to 20 synchronous wave sources on the center and a screen on the right.

The instantaneous intensity is drawn on a plane through the sources and on the screen (on the right). If average is positive, the third image displays the intensity averaged over average frames.
Unit length is equal to the distance between sources and screen.
On the left one can choose the number of sources, their wavelength λ and the phase velocity v.
One can also change the distance between sources a.
To get information on an element, put over it the mouse pointer to see the corresponding tooltip.

Activities

Your main goal is to recover the results of the theoretical analysis in which it is assumed that the screen (observation point) is at infinity.
Discuss, for instance, the directions of maximum intensity for a = λ/2 and N = 4. Use the simulation to check your calculation.
Try different values for λ and a. Discuss the numerical artifacts introduced by the discretization of space.
What happens when one changes Δt? Why? (Try also 'odd' values like 0.0017.)
And whith different values of average?

This is an English translation of the Basque original for a course on mechanics, oscillations and waves.
It requires Java 1.5 or newer and was created by Juan M. Aguirregabiria with Easy Java Simulations (Ejs) by Francisco Esquembre. I thank Wolfgang Christian and Francisco Esquembre for their help.