Download HW17 - University of St. Thomas

Physics 112 HW17
/5
Due Monday, 31 October 2016
QVB02. A particle with mass 1.81 g and a charge of 12.2 nC has, at a given
instant, a velocity v = (30,000 m/s)ĵ. What are the magnitude and direction of
the particle’s acceleration produced by a uniform magnetic field B = (1.63 T)î
+ (0.980 T)ĵ?
QVB03. An electron moves at 2,500,000 m/s through a region in which there is
a magnetic field of unspecified direction and magnitude 0.0740 T.
a) What are the largest and smallest possible magnitudes of the acceleration
of the electron due to the magnetic field?
b) If the actual acceleration of the electron is ¼ of the largest magnitude in
part a), what is the angle between the electron velocity and the magnetic
field?
Nikola Tesla (1856-1943)
QVB04. An electron at point A in the diagram at right has a speed vo of
1,410,000 m/s.
a) Find the magnitude and direction of the magnetic field that will cause
the electron to follow the semicircular path from A to B.
b) Find the time required for the electron to move from A to B.
vo
A
10.0 cm
QVB05. In an experiment with cosmic rays, a vertical beam of particles that
have charge of magnitude 3e (e is the charge of a single proton) and mass
12 times the proton mass enters a uniform horizontal magnetic field of
0.250 T and is bent in a semicircle of diameter 95.0 cm, as shown in the
figure at right.
a) Find the speed of the particles and the sign of their charge.
b) Is it reasonable to ignore the gravity force on the particles?
c) How does the speed of the particles as they enter the field compare
to their speed as they exit the field?
QVB06. (Toughie!) A velocity selector consists of perpendicular electric and
magnetic fields as shown in the diagram at right.
a) What strength magnetic field is needed so that only ions of speed 2000
km/s will emerge undeflected, if the electric field is 200,000 N/C? Will
positive ions be separated from negative ions?
b) In a certain velocity selector, the electric field is produced by a variablevoltage battery connected across large, parallel, metal plates that are
separated by 3.25 cm, and the magnetic field comes from an
electromagnet whose field strength can be varied. If the battery voltage
can range between 120 V and 560 V and the magnetic field between
0.054 T and 0.180 T, what range of ion
velocities can this selector be adjusted to
produce?
B
95.0 cm
B
+ q
v
    
    
    
B
    
  E  