Two-Source Interference in a Ripple Tank

Theory

Two in-phase sources produce constructive interference where the path difference is $\Delta r=m\lambda$ and destructive interference where $\Delta r=(m+\frac{1}{2})\lambda$. Here $\lambda =v/f=3/1.5=2$ m.

What to observe

• Calm “still” bands (nodal lines) radiate from the sources.

Try this

• Select the tank and switch to Average intensity.
• Change the phase of one source to 180°.
• Increase the frequency: the fringes get closer.

Also available in: Interferência de duas fontes na cuba de ondas (Português) · Interferencia de dos fuentes en la cubeta de ondas (Español)