Selector on every radio button click
I don't think your approach 2 will do what you want. So I the first one would be better.

It looks to me though that you are building another selector. Probably to find the child element. So I would recommend something like this:

var $c = $t1.find("." + $(this).attr("mobnum")).


This returns the child element. This way you are already selecting only out of the children of $t1. Which would be more efficient, in theory.