r$\_($a$)$ r$\_($b$)>$r$\_($a$)$ n$\_($a$)$ and n$\_($b$)$

turns per unit length, respectively. The solenoids carry

the same current, but in opposite directions. Let r be

the radial distance from the common axis of the

solenoids.

Part A

If the magnetic field inside the inner solenoid $($n$\_($b$))/($n$\_($a$))($n$\_($b$))/($n$\_($a$))=$r$\_($a$)$