changing prompt for super user

[Dan Murphy]

Hi all.
I was wondering if there is any way that I can set things up so I can
change the appearance of the prompt when I switch to super user after
logging in as a regular user?
In other words, if I log in as mweeby and then use the su command to use
root privileges, can I change the prompt so that as long as I am su it's
different?
If nothing else, could somebody indicate what man pages I should look at.
Thanks.