## PHYS208 Fundamentals of Physics II

### Hint for Ch. 31, 5Q

a) What direction is B due to the induced current directed?

b and c) What is the difference in the change of magnetic flux when loop 2 is compared to loop 1?

### Hint for Ch. 31, 10P

Keep in mind that the axial field outside a long solenoid is zero. What is the correct area to use for the flux determination -- the cross-sectional area of the solenoid or the area of the 120-turn coil?

### Hint for Ch. 31, 21P

Assign a directed area vector to the loop to determine the total change in magnetic flux when the loop is flipped. Also note that the axis of the coil is at 20 degrees, not 70 degrees, from the magnetic field of the Earth.

### Hint for Ch. 31, 25P

a) Assign a directed area vector to the loop and determine the magnetic flux. Consider the time rate of change of flux as the angle 2pi f t varies with time.

"http://www.physics.udel.edu/~watson/phys208/exercises/hints/0415.html"
Last updated April 15, 1998.
Copyright George Watson, Univ. of Delaware, 1997.