Imagine repeating the experiment in an airleas tube or vacuum ​

If you imagine thhat you will repeat the experiment in an airleas tube or a vacuum is that if you repeat the experiment with the airleas tube that you will noot be able to use more air to blow or add air to your experiment but if you use a vacuum you can keep reusing the air because the filters in the vacum produces clean air.

Explanation: I am not sure this is the answer is what you were looking for. If this is Wrong im sorry.

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: