Why is the "bending" of waves related to wavelength? Hi! As stated in the title, my question concerns the "bending" of waves. (I'm quite sure that "bending" is not the proper term, so if you know the correct one, please tell me.) Let's say that we investigate waves in a ripple tank. We create a plane wave and put a blockage, parallell to the wavefront, with a small slit in it. If the slit is small enough, we will get almost circular waves on the other side of the blockage, but if the slit is large, the wave on the other side will not be as much bent. This seems natural to me, but I don't understand how it is related to wavelength. My questions are: 1. In our physics textbook, there was an inequality for "bending" of waves in an experiment like the one described above: D[tex]\leq[/tex][tex]\lambda[/tex], where D is the width of the slit and lambda is the wavelength. What do they mean by this? The bending of the waves gets less and less, the wider the slit is, but it never disappears. How then, can you give such a condition for "bending". 2. Why does the wavelength affect the "bending" of the waves? Thanks in advance!