[填空题]
A 32-cm-long solenoid, 1.8 c , jjcpnc(2rm,m in fave1n7 2+emj:be,0v8isb0mybq 1radiameter, is to produce a 0.30-T magnetic field at its center.vryb:ee0 2aan+sim0fbv qb8m1 7je1, If the maximum current is 5.7 A, how many turns must the solenoid have? $ \times10^{4 }\;turns$
