Question

[1] (similar to chapter 21, problem 5b). Find the magnitude of the minimum velocity

of charge q=+2e that will produce the magneticforce F shown in Fig. 21–62.

text 5Chapter title

Question

[2] (similar to chapter 21, problem 8). The magnetic field near the surface of a neutron

star hasa magnitude of 1E8 T. Find the acceleration of anelectron near the star moving at 1E7 m/s if bothv and B are in the same plane, with B directed to

theright and v directed 30.0 degrees above B.

text 8.

Question

[3] (similar to chapter 21, problem 12). Find the magnitude and direction of the weakest

mag -netic field required to levitate a wire of length

5.00 cmand mass 2.00 g, carrying a current of 8.00 A.

text 12.

Question

[4] (similar to chapter 21, problem 19). Find the minimum current that must pass through

the coilof an electric motor to produce a torque of 20.0 N-

m ifthe coil consists of 200 turns enclosing an area of

300 cm2and the magnetic field strength is 0.400 T.

text 19.

Question

[5] (similar to chapter 21, problem 24) A singly charged Li ion has a mass of 1.16E-26 kg.It is accelerated through a potential difference of 500 Vand subsequently enters a uniform magnetic field ofmagnitude 0.400 T perpendicular to the ion’s velocity.Find the radius of its path.

text 24.

Question

[6-7] (similar to chapter 21, problem 26ab)

In a region where there is a uniform 0.200 T magnetic

field perpendicular to the xy plane, a stream of protons

is to be shot from the origin at a fixed initial speed v0

(Fig. 21–71).(a) At what angle theta-0 must the

velocity vector v0 be directed in order for the protons to reach as great a height y as possible?

(b) If the maximum height is 1.00 m, what is the initial speed of the protons?

text 26.

Question

[8] (similar to chapter 21, problem 31)Find the strength of the magnetic field 1.00 cm from apower line carrying a current of 125 A.

text 31.

Question

[9-10] (similar to chapter 21, problem 35ab)The earth’s magnetic field at the magnetic north pole isdirected vertically downward and has a magnitude of0.62 G. The earth’s field is approximately that of a cur -rent loop located at the center of the earth.[9] Find the magnitude and direction of the earth’s mag -netic moment.[10] It is believed that the earth’s magnetic field is pro -duced by electric current in the earth’s liquid metallicouter core. Suppose that the magnetic moment wereproduced by a current through a simple circular pathof radius equal to the average radius of the outercore (2300 km). Find the direction and magnitude ofthis current.

text 35.

Question

[11] (similar to chapter 21, problem 47)A cylindrical permanent magnet has a volume of 200

cm^3and a uniform magnetization of 1E6 A/m along itsaxis. The magnet is placed in a uniform external mag -netic field of magnitude 0.40 T. The magnet’s

magnetizationvector is initially at an angle of 30 degrees with thedirec tion of the external field. Find the magnetic torqueexerted on the magnet.

text 47.

Question

[12] (similar to chapter 21, problem 48)A cylindrical electromagnet contains a uniformly mag -netized core having a magnetization of 1.7E6 A/m,surrounded by a coil 20 cm long with 3000 turns of wirecarrying a current of 4.0 A. Find the magnetic field inthe core

text 48.