Download Magnetic Forces and Magnetic Fields Discussion Questions 1

Chapter 21 Discussion
January-03-15
8:58 PM
Magnetic Forces and Magnetic Fields
Discussion Questions
1: When an electrically charged particle is placed near a magnet, does
the magnet exert a force on the particle? If so, does a North pole
repel or attract a positively-charged particle?
2: If you cut a bar magnet in half, will you then end up with an
isolated North pole and an isolated South pole? Will the two isolated
poles then attract each other?
3: The magnitude of the electric field at a certain location in space is
200 (in the usual SI units) and the magnitude of the magnetic field at
the same location is 300 (in the usual SI units). If the directions of the
two fields are the same at this certain location, can we then say that
the magnitude of the electromagnetic field is 200 + 300 = 500 units at
this location?
4: Does the superposition principle apply to magnetic fields and
magnetic forces?
5: The textbook makes a big deal about electric potential, but says
nothing about magnetic potential. Why not?
6: Consider the magnetic field as you move away from a wire that
carries an electric current, along a line perpendicular to the wire.
Does the magnitude of the magnetic field decrease in the same way
as the electric field strength due to a point charge or the gravitational
field strength due to a point mass? That is, is magnetism also an
inverse-square force?
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inverse-square force?
7: What happens to the magnetic field strength inside a solenoid
when you wrap the wire into turns that have a larger radius, while
keeping the number of turns per unit length constant?
8: An electrically charged particle is at rest in a region of space that
has a uniform magnetic field. If the charge on the particle suddenly
doubles, and the magnetic field remains the same, describe how the
magnetic force on the particle changes.
9: An electrically charged particle moves at a constant speed parallel
to a uniform magnetic field. If the speed of the particle suddenly
doubles, and the magnetic field remains the same,
(a) describe how the magnetic force on the particle changes.
(b) describe how the path of the particle changes.
10: An electrically charged particle moves at a constant speed
perpendicular to a uniform magnetic field. If the speed of the particle
suddenly doubles, and the magnetic field remains the same,
(a) describe how the magnetic force on the particle changes.
(b) describe how the path of the particle changes.
11: For two parallel wires, is the force between them attractive or
repulsive if
(a) the currents in the wires are in the same direction.
(b) the currents in the wires are in opposite directions.
12: When a current-carrying loop of wire is placed in a uniform
magnetic field, does the force exerted by the magnetic field on the
current loop tend to twist the loop so that its symmetry axis becomes
more parallel to the magnetic field or more perpendicular to the
magnetic field?
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13: Explain how a motor works.
14: Explain how a mass spectrometer works.
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