The magnetic field inside a solenoid can be found exactly using ampère's law only if the solenoid is infinitely long. otherwise, the biot-savart law must be used to find an exact answer. in practice, the field can be determined with very little error by using ampère's law, as long as certain conditions hold that make the field similar to that in an infinitely long solenoid.

which of the following conditions must hold to allow you to use ampère's law to find a good approximation?

(a) consider only locations where the distance from the ends is many times d.
(b) consider any location inside the solenoid, as long as l is much larger than d for the solenoid.
(c) consider only locations along the axis of the solenoid.

On a horizontal frictionless surface, a small block with mass 0.200 kg has a collision with a block of mass 0.400 kg. immediately after the collision, the 0.200 kg block is moving at 12.0 m/s in the direction 30° north of east and the 0.400 kg block is moving at 11.2 m/s in the direction 53.1° south of east. use coordinates where the +x-axis is east and the +y-axis is north.(a) what is the total kinetic energy of the two blocks after the collision (in ) what is the x-component of the total momentum of the two blocks after the collision? (indicate the direction with the sign of your ) what is the y-component of the total momentum of the two blocks after the collision? (indicate the direction with the sign of your answer.)