{ "items" : [
    { "id" : "http://dbpedia.org/resource/Group_velocity"
      "properties" : {
        "http://www.w3.org/2000/01/rdf-schema#comment" : [ "The group velocity of a wave is the velocity with which the overall shape of the waves' amplitudes—known as the modulation or envelope of the wave—propagates through space.For example, if a stone is thrown into the middle of a very still pond, a circular pattern of waves with a quiescent center appears in the water. The expanding ring of waves is the wave group, within which one can discern individual wavelets of differing wavelengths traveling at different speeds." ] ,
        "http://www.w3.org/2000/01/rdf-schema#seeAlso" : [ "http://dbpedia.org/resource/Plane_wave" ] ,
        "http://xmlns.com/foaf/0.1/depiction" : [ "http://commons.wikimedia.org/wiki/Special:FilePath/Wave_group.gif" ] ,
        "http://dbpedia.org/ontology/thumbnail" : [ "http://commons.wikimedia.org/wiki/Special:FilePath/Wave_group.gif?width=300"] } } }
