var fDesc=new Array(); fDesc[0] = "Ripple Tank (previously Interference) simulates the interference between two circular waves, for instance waves on water. You can make both still images and animations of the interference pattern. Change the separation or phases of the sources. This program is ideal for explaining what happens in a ripple tank. Suitable for high school and college students and teachers."; function tShowHide(id, show) { var s = document.getElementById("desc"); if ((s.innerHTML.length<=212 || show==1) && show!=2) { s.innerHTML = fDesc[id]; if (document.getElementById('m1')) document.getElementById('m1').style.display='none'; if (document.getElementById('m2')) document.getElementById('m2').style.display='none'; if (document.getElementById('more_txt')) document.getElementById('more_txt').style.display='inline'; } else { s.innerHTML = ''; } }