A rectangular loop has an area 0.75 m2, and has 100 turns of wire, that sits in the horizontal plane. A uniform magnetic field of strength 7 T, vertical, passes through the loop. The loop is turned 90◦ around one its horizontal axes, in 3× 10−2 s. What electromotive force develops in the loop?

Helmholtz coils are frequently used in experiments because they create a uniform magnetic field about their central axis. For example, they are traditionally used in the experiment for the measurement of the charge-to-mass ratio of the electron. Helmholtz coils are two coils separated by a distance equal to their radius that carry equal currents in the same direction." Suppose the radius of the coils is R 18.00 cm and each coil carries a current of /== 11.50 A and has N 340.0 turns. The coils are in the yz plane where one coil's center is at x = 0 the other coil's center is at x = R. -X=R 00

Suppose that the dipole moment associated with an iron atom of an iron bar is 2.8 x 1023 J/T. The bar is 5.2 cm long and has a cross-sectional area of 1.5 cm2. Two-thirds of the atoms have their dipole moment in one directions and remaining one-third have their dipole moment in the opposite direction. What torque (in N*m) must be exerted to hold this magnet perpendicular to an external field of 1.2 T? (The density of iron is 7.9 g/cm3 and its molar mass is 55.9 g/mol. Avogadro's number is 6.022*1023 atoms/mol.)

A positively charged particle travels in the positive x direction through a region of magnetic field in the negative y direction. In what direction is the resulting force? O negative x direction O negative z direction O positive y direction