How to determine dropped object?

How to determine dropped object?

If I've made multiple objects of a certain class droppable, is there a way to determine the jQuery object that was dropped on within the drop function?

So, in the following snippit, how can I tell specifically which object of class="photo" was dropped on?

            $('.photo').droppable({
                accept: '#jail li',
                activeClass: 'custom-state-active',
                drop: function(ev, ui) { alert('dropped');
                }
            });

Thanks.

Regards,

David