A very long coaxial cable consists of an inner thick wire (radius R) carrying a
ID: 1482558 • Letter: A
Question
A very long coaxial cable consists of an inner thick wire (radius R) carrying a current of 5A, and an outer thick wire encasing the inner wire (starting at R and going out to 2R) and carrying 5A in the opposite direction. What statement is true about how the magnetic field changes as a function of distance from the cable centre, r?
Also, please explain why.
Magnetic field is zero for r=0 to R, then increases linearly as we go from r=R to 2R
Magnetic field is 0 everywhere inside the cable.
Magnetic field increases going from r=0 to R, then decreases from r=R to 2R becoming 0 at r=2R.
Magnetic field increases linearly from the centre of the cable, until we reach r=2R.
A.Magnetic field is zero for r=0 to R, then increases linearly as we go from r=R to 2R
B.Magnetic field is 0 everywhere inside the cable.
C.Magnetic field increases going from r=0 to R, then decreases from r=R to 2R becoming 0 at r=2R.
D.Magnetic field increases linearly from the centre of the cable, until we reach r=2R.
Explanation / Answer
The correct answer is c.