Atoroid is a solenoid in the shape of a donut (fig. 20-60). use ampére's law along the circular paths, shown dashed in fig 20-60a, to determine that the magnetic field
a) inside the toroid is b= u0 ni/2pir where n is the total number of turns
b)outside the toroid is b=0
c)if not, how does it vary?

To practice problem-solving strategy 10.1 for energy conservation problems. a sled is being held at rest on a slope that makes an angle θ with the horizontal. after the sled is released, it slides a distance d1 down the slope and then covers the distance d2 along the horizontal terrain before stopping. find the coefficient of kinetic friction μk between the sled and the ground, assuming that it is constant throughout the trip.