Can somebody briefly explain me the tension of the string, and has it any relation to any of the newton s laws?

Explanation:

I'll give it a go.

In simpler cases, tensions in strings are typically caused by some weight attached to the end of them. You could use Newton's 3rd Law to describe this phenomenon.

So because the weight is pulling on the rope with a force, an equal and opposite force is enacted throughout the rope. That equal and opposite force is what we call "tension".

*Note that if the weight of the rope is negligible, or you are ignoring it for a specific problem, then the tension is the same throughout the rope. In more complicated cases, the rope does have weight. In these cases the tension changes at different lengths of rope.

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:

wire in brush may conduct electricity from cell to drill and vice versa electrc shock possible