<html lang="en" dir="ltr">
<head>
<meta charset="utf-8">
<title></title>
<script>
function check_value(onoff){
switch(onoff){
case "On":
document.getElementById("myImage").src = "images/pic_bulbon.gif";
break;
case "Off":
document.getElementById("myImage").src = "images/pic_bulboff.gif";
break;
}
}
</script>
</head>
<body>
<img id="myImage" src="images/pic_bulboff.gif" style="width:100px">
<form method="post" action="">
<input type="radio" name="switch" value="On" onchange="check_value(‘On’)"> On<br>
<input type="radio" name="switch" value="Off" onchange="check_value(‘Off’)" checked="checked"> Off<br>
</form>
</body>
</html>
[/code]