How to change a image on mouseover?

<script type="text/javascript">
var img1="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjbbgq8BX0QW2994ow7-4NfAM2MOeG9v60cV_6EAIlE5uFph1A3On_euP0OqawI5T1g9e6SDWMNNPRZQFU6litCkinLag5LJBfNG4CcA6lyWthG1x7rmALMuGLFmMKF-KV9a0Hq_vYW8n7b/h120/javascript_logo.png";
var img2="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi1S_ZRXkZ4OGIya2nR2ayDEUMVUw8MJriLqE_XeetsdpDWWby80gQMhhXRjCi7ib2URtzuAmsR3xvWBMhTtshgMte02oNV52UPlgjai2drRCQufFpRC7rbq7Bft2mjyzYhX66EVxB8RSGl/h120/psd_of_html5_logo_by_tobrother-d37hlwk%255B1%255D.png";
function Switch(){
if(document.getElementById("img").src==img1){
document.getElementById("img").src=img2;
}
else{
document.getElementById("img").src=img1;
}
}
</script>
<img id="img" onmouseover="Switch()" onmouseout="Switch()" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjbbgq8BX0QW2994ow7-4NfAM2MOeG9v60cV_6EAIlE5uFph1A3On_euP0OqawI5T1g9e6SDWMNNPRZQFU6litCkinLag5LJBfNG4CcA6lyWthG1x7rmALMuGLFmMKF-KV9a0Hq_vYW8n7b/h120/javascript_logo.png">

Result: