A Current Is Used to Charge a Capacitor $B = \frac { \mu _ { 0 } I } { 2 \pi r }$

Multiple Choice

A current is used to charge a capacitor. After the capacitor has been charged, the magnetic field between the plates is

A) given by $B = \frac { \mu _ { 0 } I } { 2 \pi r }$
B) given by $B = \frac { \mu _ { 0 } I ^ { 2 } } { 2 \pi r }$
C) given by $B = \frac { \mu _ { 0 } I } { 2 \pi r ^ { 2 } }$
D) zero.