III.
Are these sentences true or false?
1.
If two bar magnets are brought close together, the like poles will
attract each other, and the unlike poles repel each other.
2.
A current generates a magnetic field, and the field differs as the
current is shaped into a loop, solenoid, toroid.
3.
Magnetic field lines, not analogous to electric field lines, describe the
force on magnetic particles placed within the field.
4.
A loop of current in a magnetic field can experience a torque if it is
free to turn.
5.
The direction of the force may be found by the left
‐
hand rule.
IV.
Think and answer.
In summary, the electromagnetic field carries energy, linear momentum
and angular momentum. It is thus appropriate to say that the
electromagnetic field moves. The motion of the electromagnetic field can be
visualized as the motion of its electric and its magnetic field lines. The
motion of the electromagnetic field is described by a least action principle.
The motion conserves energy and momentum. The motion is continuous,
relative, reversible and mirror-invariant. We are directly led to ask: what is
the nature of light then?
V.
Render the text into English.
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