Problem 1
A coil of 17 cm in diameter and wound with three turns of wire is placed with the plane of the coil at right angles to a magnetic field of 3.8 x 10^-2 T. What emf is induced in the coil if
a) the field is halved in 0.27 s,
b) the field is reversed in 0.27 s,
c) the coil is rotated through an angle of 90^o about its diameter in 0.27 s.


Ans. a) 4.8 mV, b) 19 mV, c) 9.6 mV


Problem 2
A proton of charge +1.60 x 10^-19C and mass 1.67 x10^-27 kg is introduced into a region of B = 1.15 T with an initial velocity of 1.25 x 10⁶ m/s perpendicular to B. What is the radius of the proton's path?

Ans. 1.13 cm


Problem 3
A long solenoid has 1400 turns per meter of length, and it carries a current of 3.5 A. A small circular coil of wire is placed inside the solenoid with the normal to the coil orientated at an angle of 90.0^o with respect to the axis of the solenoid. The coil consists of 50 turns, has an area of 1.2 x 10^-3 m², and carries a current of 0.50 A. Find the torque exerted on the coil.

Ans. 1.8 x 10^-4 Nm


Problem 4
Consider the arrangement shown below. Assume that R = 60.0 W and L = 1.2 m, and that a uniform 2.5-T magnetic field is directed into the page.
a) At what speed would the bar be moved to produce a current of 0.60 A in the resistor?
b) In what direction is the current? Explain.



Ans. a) 12 m/s, b) counterclockwise

Problem 5
An 8.2 mH inductor is connected to an ac generator which has a frequency of 620 Hz and a V_rms equal to 10.0 V. Determine the maxiumum value of the current supplied by the generator.

Ans. .44 A

Problem 6
The triangular loop of wire shown in the drawing carries a current of I = 4.70 A. A uniform magnetic field is directed parallel to side AB of the triangle and has a magnitude of 1.80 T.
a) Find the magnitude and direction of the magnetic force exerted on each side of the triangle.
b) Determine the magnitude of the net force exerted on the triangle.




Ans. a) F_AB = 0, F_AC = 24.2 N into the paper, F_CB = 24.2 N out of the paper, b) Zero

Problem 7
The drawing shows two long, straight wires that are suspended from a ceiling. The mass per unit length of each wire is 0.050 kg/m. Each of the four strings suspending the wires has a length of 1.2 m. When the wires carry identical currents in opposite directions, the angle between the strings holding the two wires is 15^o. What is the current in each wire?



Ans. 320 A