Loop 1 Loop 2 Figure P20.53

Figure P19.64 is a setup that can be used to measuremagnetic fields. A rectangular coil of wire contains N turnsand has a width w. The coil is attached to one arm of a balanceand is suspended between the poles of a magnet. The fieldis uniform and perpendicular to the plane of the coil. Thesystem is first balanced when the current in the coil is zero.When the switch is closed and the coil carries a current I, amass m must be added to the right side to balance the system.(a) Find an expression for the magnitude of the magneticfield and determine its direction. (b) Why is the result independentof the vertical dimension of the coil? (c) Supposethe coil has 50 turns and width of 5.0 cm. When the switch is closed, the coil carries a current of 0.30 A, and a mass of 20.0 gmust be added to the right side to balance the system. What isthe magnitude of the magnetic field?

A piece of copper wire has a resistance per unit length of 4.63 × 10/m. The wire is wound into a thin, flat coil of many turns that has a radius of 0.208 m. The ends of the wire are connected to a 12.0-V battery. Find the magnetic field strength at the center of the coil. Number i Units >

There are two concentric tungsten wire loops; a 4 cm radius loop and a 33 cm radius loop. The cross-sectional area of each wire is 0.009 m2. The current in the larger loop goes from 0 A to a counterclockwise 9 A in 5.9  10-4 s. Find the voltage & current in the smaller loop during the stated time interval. Assume the B-field of the larger loop is uniform (though not constant) across the smaller loop. V = I =