Hey dear,
The drift velocity is the average velocity of the charge that resides in the conductor. So we can say that the drift velocity is directly proportional to the relaxation time ,which means as the drift velocity increases relaxation time also increases and vice versa reason being the charge carries have more time to accelerate between collisions..
Thank you!!

Hello Tanu!

The drift velocity is just the average velocity of the charge carriers in the conductor. So, as you now see, the drift velocity is proportional to the relaxation time . As the relaxation time increases the drift velocity increases, because the charge carriers have more time to accelerate between collisions.

Hope this will help you!

Thank you!