Do a full backup or differential backup will clear the tran_log?

I am interested to see your response and a justification for your answer is most accepted.

Answer(Posted on 19th May 2011) :

Let me come up with the answer of this question : No,fullbackup and differential backup wont clear the tran_log.A part of tran_log is backed up to ensure consistency,however the log is never cleared.

Tran_log backup in full recovery mode will ensure that your tran_log is truncated.