Download On-Line TEST on Ch.30

AP Physics C - Online Test on Ch.30 - Sources of the Magnetic Field. Worth 105 pts @ 15.
Solve using a word-processing system, no scanning or paint. Send as a Wordfile or PDF.
The deadline is March 31, 2010 before 8:00 PM. No Exceptions or you get a zero!
Show all work. No name, no credit.
1.
A long solenoid (n = 80 turns/cm) carries a current of 70 mA. If the interior of the solenoid is filled
with a ferromagnetic material having a permeability km of 650, determine the magnitude of the
magnetic field before and after the ferromagnetic material is inserted.
2.
Two wires, each having a weight per unit length of 10 –4 N/m, are strung parallel one
0.1 m above the other. If the wires carry the same current, though in opposite directions, how great
must the current in each wire be for the magnetic field of the lower conductor to balance the weight
of the upper conductor?
3.
What current in a solenoid 15-cm long wound with 100 turns would produce a magnetic field equal
to that of the Earth, 5 x 10–5 T?
4.
A superconducting wire carries a current of 1.0 x 10 4 A. Find the magnetic field at a distance of 1.0
m from the wire.
5.
The planetary model of the hydrogen atom consists of an electron in a circular orbit about a proton.
The motion of the electron of charge 1.6 x 10–19 C creates an electric current. The radius of the
electron orbit is 5.3 x 10–11 m and the electron's velocity is 2.2 x 106 m/s. What is the magnetic field
strength at the location of the proton?
6. A solenoid 4.0 cm in radius and 4.0 m in length has 8000 uniformly spaced turns and carries a
current of 5.0 A. Consider a plane circular surface (radius = 2.0 cm) located at the center of the
solenoid with its axis coincident with the axis of the solenoid. What is the magnetic flux through
this surface?
7.
A straight wire (length = 8.0 m) is bent to form a square. If the wire carries a current of
20 A, what is the magnitude of the magnetic field at the center of the square?