Unformatted text preview: Physics 21 Fall, 2004 Solution to HW-14 28 P 46 An iron core solenoid is 38 cm long, 1.8 cm in diameter, and has 600 turns of wire. A magnetic field of 2.2 T is produced when 48 A ﬂows in the wire. What is the permeability at this high field strength? The expression for the magnetic field in the iron core of the solenoid is B = µnI , where the number of turns per meter is n = N/L . Combining these equations gives B = µN I/L ⇒ µ = BL/N I. Substituting numbers gives µ = 2 . 2 × . 38 600 × 48 = 2 . 90 × 10- 5 Tm / A . 28 P 58 Two large coils of wire, each with N turns carrying a current I and separated by a distance equal to the radius R of the coils, are called Helmholtz coils . (a) Determine B at points x along the line joining their centers. Let x = 0 at the center of one coil, x = R at the center of the other. (b) Plot B versus x from x = 0 to x = R . (c) Determine B on the axis midway between the coils ( x = R/ 2) if R = 20 . 0 cm, I = 35 A, and each coil contains N = 350 turns.= 350 turns....
View Full Document
This note was uploaded on 08/06/2008 for the course PHYS 21 taught by Professor Hickman during the Fall '07 term at Lehigh University .
- Fall '07