Figure 7.1-For Problem 5 6. A brass ring with triangular cross section encircles a very long straight wire concentrically as in Figure 7.2. If the wire carries a current I, show

that the total number of magnetic flux lines in the ring is 2mb [b- ana+b] 2πb Calculate if a = 30 cm, b = 10 cm, h = 5 cm, and I = 10 A. Brass ring Figure 2.- Cross section of a brass ring enclosing a long straight wire; for Problem 6 7. Consider the following arbitrary fields. Find out which of them can possibly represent an electrostatic or magnetostatic field in free space. a) A = y cos ax ax + (y + e*)a₂ 20 b) B==a c) C = r² sine a/n