A - Complete with gerund or infinitive1) It's very expensive a flat in the centre. (rent) 2) Are you afraid of ? (fly)
3) I called the restaurant a table for tonight. (book)
4) Be careful a noise when you come home tonight. (not make)
5) She's worried about the exam. (fail)
6) Everybody went on until after midnight. (dance)
7) an only child is a bit boring. (be)
8) It's easy the way if you look at the map. (find)
9) He's terrible at languages. (learn) 
10) A- Why are you learning Spanish?
B- talk to my in-laws. They're Argentinian, and they don't speak English. (be able to)

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:

d.7.5cm is your answer