Consider an Ideal Solenoid of Length L, N Windings, and Radius

Multiple Choice

Consider an ideal solenoid of length L, N windings, and radius b (L is much longer than b) . A current I is flowing through the wire windings. If the radius of the solenoid is doubled to 2b, but all
The other quantities remain the same, the magnetic field inside the solenoid will

A) become one-half as strong as initially.
B) remain the same.
C) become one-fourth as strong as initially.
D) become twice as strong as initially.
E) become four times as strong as initially.