dropdown menu over effect with jquery

$(document).ready(function(){
//dropdown menu over effect

$("ul#mainmenu li ul.dropdown").css('opacity', 0.0); //hide dropdown normal
$("ul#mainmenu li").hover(function(){

$(this).find("ul.dropdown").stop().animate({opacity: 1}); //show dropdown when hover mouse on li

},
function(){
$(this).find("ul.dropdown").stop().animate({opacity: 0.0});//hide dropdown when leave  mouse from li

}

);

});