Physics 236 Worksheet: Chapter 29, Magnetic Force (1)

 

1.     The magnetic force on a moving charge is able to

a.     change both the speed and direction of the charge.

b.      change the speed but not the direction of the charge.

c.      change the direction but not the speed of the charge.

2.     A positive charge moving to the east enters a magnetic field directed straight up. The magnetic force on the charge is directed

a.     up.

b.      down.

c.      to the east.

d.     to the west.

e.     to the north.

f.       to the south.

3.     The circular and square loops on the right carry
the same clockwise current. The diameter of the
circle is equal to a side of the square.

a.     The torque on the circular loop is greater than the torque on the square loop.

b.      The torque on the circular loop is less than the torque on the square loop.

c.      The torque on the circular loop is equal to the torque on the square loop.

d.     The torque on both loops is zero.

4.     A proton and an alpha particle are accelerated through the same potential difference and the enter the same perpendicular magnetic field. (An alpha particle has a charge of +2e and a mass of four protons. m_a = 4m_p) The radius of the alpha particle’s orbit is

a.     the same as the radius of the proton’s orbit.

b.      twice the radius of the proton’s orbit.

c.      one half the radius of the proton’s orbit.

d.     equal to     times the radius of the proton’s orbit.

e.     equal to          times the radius of the proton’s orbit.

5.     A transmission line carries current to the east. The line is in a magnetic field directed north. The magnetic force on the wire is directed

a.     up.

b.      down.

c.      north.

d.     south.

e.     east.

6.     The density of the current carriers is a material can be measured using

a.     a mass spectrometer.

b.      a cyclotron.

c.      a velocity selector.

d.     the Hall effect.

7.     If the magnetic field of a cyclotron is doubled, the maximum kinetic energy it can deliver is

a.     not affected.

b.      doubled.

c.      increased by a factor of four.

d.     increased by a factor of eight.

 

Ans: 1-c, 2-f, 3-b, 4-d, 5-a, 6-d, 7-c

 

Physics 236 Worksheet: Magnetic Force (2)

 

In each case calculate the x, y, and z components and the magnitude of the magnetic force on a moving charge at the origin. Use: q = +1.0 C, v = 2.0 m/s, B = 0.5 T

 

 

                                                                  

 

 

 

 

 

 

 

 

 

          (a)  F = 1.0 T k                                          (b) F = 1.0 T j

 

 

 

 

 

                                     

 

 

 

 

 

 

          (c) F = -0.5 T k                                         (d) F = 0                             

 

 

                            

 

 

 

 

 

 

 

 

 

 

 

          (e) F = (1.73 j – 1.0 k) T                             (f) F = (0.49 i –0.41 j – .59 k) T