Earth's magnetic field is similar to that of a bar magnet. select all the statements that are true as a consequence of this. a. it has a north and south magnetic pole. b. it has a bar-shaped iron section inside it. c. its magnetic field lines form closed loops. d. magnetic objects are attracted to its poles.

I believe the answer will be...

 A. It has a north and south magnetic pole

a solenoid is created by wrapping a l = 90 m long wire around a hollow tube of diameter d = 4.5 cm.   the wire diameter is d = 0.9 mm.   the solenoid wire is then connected to a power supply so that a current of i = 9 a flows through the wire.

randomized variablesl = 90 m

d = 4.5 cm

d = 0.9 mm

i = 9 a                                          

write an expression for the number of turns, n, in the solenoid. you do not need to take into account the diameter of the wire in this calculation.

calculate the number of turns, n, in the solenoid.

write an expression for the length of the solenoid (l2) in terms of the diameter of the hollow tube d.

calculate the length of the solenoid (l2)   in meters.

calculate the magnitude of the magnetic field at the center of the solenoid in teslas.

explanation:

c) up is the direction the magnetic force is acting on the charge.