Question

1. To construct a solenoid, you wrap insulated wire uniformly around a plastic tube 8.7 cm in diameter and 30 cm in length. You would like a 3.0 A current to produce a 2.5 kG magnetic field inside your solenoid. What is the total length of wire you will need to meet these specifications?

2. Experiments carried out on the television show Mythbusters determined that a magnetic field of 1000 gauss is needed to corrupt the information on a credit card's magnetic strip. (They also busted the myth that a credit card can be demagnetized by an electric eel or an eelskin wallet.) Suppose a long, straight wire carries a current of 3.5 A .How close can a credit card be held to this wire without damaging its magnetic strip?

Answer 1

1-

diameter of plastic tube d = 0.087m

length of tube L= 0.3m

current passing through wire I = 3 A

magnetic field produced by it B = 2.5 kG

     we have

      N =BL/?₀I

          =(2.5*10³G)(10^-4T/1G)(0.3m)/(4*pi*10^-7Tm/A)(3A)

         Thetotal length of the wire is

       L ' = N*circumference ofthe tube

            = {(2.5*10³G)(10^-4T/1G)(0.3m)/(4*pi*10^-7Tm/A)(3 A)} *{pi*(0.087m)}

            = 5.44 km

kindly ask next question in new post.