Ch.29 Classwork Solutions
z
e+
v
x
y
B
60o
The Magnitude of this Moment is in­calcuable!
A rectangular coil of dimensions (5.4 cm by 8.5 cm) consists of 25 turns of wire. The coil carries a current of 15.0 mA.
a) Calculate the magnitude of it's magnetic moment.
b) Suppose a magnetic field of magnitude 0.35 T is applied parallel to the plane of the loop. What is the magnitude of the torque acting on the loop?
c) Suppose now that the magnetic field makes an angle of 60 degrees with μ, find the torque.
d) Suppose that the magnetic field makes an angle of zero degrees with μ, what is the torque?
Beam Me Up James Doohan!
In an experiment designed to measure the strength of a uniform
magnetic field a beam of electrons is accelerated from rest through a
potential difference of 350V, and the beam of electrons is measured
to have curved into a circle of radius 7.5 cm. Assuming the magnetic
field is perpindicular to the beam...
a) What is the magnitude of the magnetic field?
b) What is the angular frequency of the electrons?
c) what is the period of revolution of the electrons?
MASS SPECULATION
1. One type of mass spectrometer uses the layout shown below. The dots represent a uniform magnetic field of 0.800 T out of the page. The parallel arrows represent an electric field of 200 kV/m. Suppose the source emits hydrogen ions and isotopes are detected at radii of 3.26 mm and 6.56 mm. (a) Find the velocity required of ions to pass through the electric field without being deflected. (b) Find the masses of the two isotopes.
2. Refer to the diagram in the previous problem. Suppose singly ionized chlorine atoms are emitted by the source and that two isotopes are present: 17 Cl35 (m = 5.85 × 10 −26 kg) and 17 Cl37 (m = 6.18 × 10 −26 kg). The fields are B = 0.50 T and E = 40.0 kN/C. (a) What is the distance between the two points where the ions hit the detector? (By how much are the ions separated?) (b) What design changes would make a mass spectrometer like this one more sensitive to differences in mass? Explain.