A long coaxial cable consist of two thin-walled conducting cylinders with inner radius 2 cm an outer radius 8 cm. the inner cylinder carries a steady current 0.1 A, and the outer cylinder provides the return path for that current. The current produces a magnetic field between the two cylinders. Find the energy stored in the magnetic field for length 5 m of the cable. Express answer in nJ (use In2=0.7) |
A long coaxial cable consist of two thin-walled conducting cylinders with inner radius 2 cm an outer radius 8 cm. the inner cylinder carries a steady current 0.1 A, and the outer cylinder provides the return path for that current. The current produces a magnetic field between the two cylinders. Find the energy stored in the magnetic field for length 5 m of the cable. Express answer in nJ (use In2=0.7) |
(7)
The magnetic field inside is only due to current of the inner cylinder
Magnetic field energy density is not uniform in the space between the cylinder. At a distance from the centre
Energy in volume of element (length )
Using values, we get nJ