Magnetic Field Due to a Solenoid A solenoid is made by tight

Magnetic Field Due to a Solenoid A solenoid is made by tightly trapping wire around a plait tube in a single layer, as shown in the figure The wire Has a diameter of 1.2 mm How much current is needed to produce a 02 T magnetic field ? Suppose the tube is 30 cm long and it has a diameter of 6 cm. Ultimate the length of wire which he would need to make the solenoid.

Solution

B = mu₀*i*n , n is number of loops per unit length
1.2 mm is 1 loop therefore 1 m is 1/0.0012 loops = 833.33

So, 0.2 = 4*pi*10^-7*833*i
So, i = 0.2/(4*pi*833*10^-7) = 191.06 A

number of loops = 833.33*0.3 = 250
And circumference = pi*0.06 = 0.18849 m

Total length = 0.18849*250 = 47.122 m