1. a) [4] The one-dimensional wave equation for a string is T (Sizyilx2 = m c'izyiat2 Where did this equation come from (that is, is it basic, or is it derived from more basic principles - and if so, what is that basic principle or principles)? b) [4] The one-dimensional wave equation for an electric field wave in vacuum is azEyiax2 = pose azEylatz. Where did this equation come from (that is, is it basic, or is it derived from more basic principles - and if so, what is that basic principle or principles)? 0) [3] Where does co/k =v = \\i(1/souo) = 0 come from? d) [3] Ey(x,t) = Easin(kx+mt) is a wave that moves in the [positive or negative] x direction