if( document.images ) { //check that changing images is supported
  var overImgA = new Image(); overImgA.src = "images/ohm1.jpg";
  var overImgB = new Image(); overImgB.src = "images/ohm2.jpg";
  var overImgC = new Image(); overImgC.src = "images/ohm3.jpg";
  var overImgD = new Image(); overImgD.src = "images/ohm4.jpg";
  var overImgE = new Image(); overImgE.src = "images/ohm5.jpg";
  var overImgF = new Image(); overImgF.src = "images/ohm6.jpg";
  var overImgG = new Image(); overImgG.src = "images/ohm7.jpg";
  var overImgH = new Image(); overImgH.src = "images/ohm8.jpg";
  var overImgI = new Image(); overImgI.src = "images/ohm9.jpg";
  var overImgJ = new Image(); overImgJ.src = "images/ohm10.jpg";
}