Showing content only in custom taxonomy posts
===

I've a custom taxonomy called **CLASS** which is hierarchial. As a Sub-taxonomy, I've **PHYSICS**.

I want to show a certain text only when users view posts (not archive pages as well) in PHYSICS taxonomy only. 

I tried the following conditional and it doesn't seem to work.


    if( ( has_term($class_id, 'class') )  && (!is_tax() ) )
    {

        //Specific code for sub-taxonomy here

    }

Here class_id stores the ID of Sub-Taxonomy (In my case for PHYSICS).

Any help would be appreciated :)

Thanks