Officially , The weber is commonly expressed in a multitude of other units : where Wb = weber , V = volt , T = tesla , J = joule , m = meter , s = second , A = ampere , Mx = maxwells .
Many times , the weber is expressed in terms of other derived units as the Tesla-square meter ( T · m2 ) , volt-seconds ( V · s ) , or joules per ampere ( J\/A ) .