Why accessing a components root element using this.$(#rootElementId) returns zero elements?

DOM

<div id="ember3705" class="ember-view">
<div id='childelement'></div>
</div>

I’m trying to execute this js code this.$('#ember3705') in component.js of the above component after it has been rendered. But it gives me zero elements as result below:

context: div#ember3705.ember-view
length: 0
prevObject: jQuery.fn.init
0: div#ember3705.ember-view
context: div#ember3705.ember-view
length: 1
[[Prototype]]: Object
selector: “#ember3705”

I’ve tried another code this.$(), this gives me the desired below result,

0: div#ember3705.ember-view
context: div#ember3705.ember-view
length: 1

My doubt is why this.$('#ember3705') gives me with no results whereas this.$() gives me results. Is this the behaviour of ember or am i missing out something?