The source of all magnetism is
moving electric charge.
The force that acts between a pair of magnetic poles depends on
magnetic pole strength.
separation distance.
Like kinds of magnetic poles repel while unlike kinds of magnetic poles
attract
Whereas electric charges can be isolated, magnetic poles
cannot
Refrigerator magnets are typically
short range
If you break a bar magnet in half you'll
have two magnets
Surrounding every magnet is
an electric field.
a magnetic field.
Magnetic fields are produced by
all moving electrical charges.
Surrounding every moving electron is
a magnetic field.
an electric field.
Magnetism is due to the motion of electrons as they
move around the nucleus.
spin on their axes.
The conventional direction of magnetic field lines outside a magnet are from
north to south.
Magnetic field strength about a magnet is strongest where magnetic field lines are
closer together
An iron rod becomes magnetic when
the net spins of many of its electrons are aligned.
The magnetic fields of a pair of nearby magnets can
add or subtract by vector rules.
The end of a compass needle that points to the south pole of a magnet is the
north pole.
A compass needle in a magnetic field
may experience a pair of torques.
Magnetic domains normally occur in
iron
In the atoms of most materials the fields of individual electrons
cancel one another.
Wood does not have magnetic properties because it contains no
magnetic domains.
To weaken a bar magnet
drop it on a hard surface.
put it in hot flames.
whack it with a hammer.
Several paper clips dangle from the north pole of a magnet. The induced pole in the bottom of the lowermost paper clip is a
north pole.
Magnetic field lines about a current-carrying wire
circle the wire in closed loops.
When current reverses direction in a wire, the surrounding magnetic field
also reverses direction.
When a current-carrying wire is bent into a loop, its magnetic field inside the loop
becomes concentrated.
A beam of electrons passing through a magnetic field experiences maximum deflection if the direction of the beam is
perpendicular to the field lines.
A beam of electrons can pass through a magnetic field without being deflected if the direction of the beam is
parallel to the field lines.
A current-carrying loop of wire experiences no tendency to rotate in a magnetic field when
no field lines pass through the loop.
A current-carrying coil of wire is
an electromagnet.
Place an iron rod inside a current-carrying coil of wire and you
increase the strength of the electromagnet.
A superconducting magnet uses
superconducting coils.
Magnet A has twice the magnetic field strength of Magnet B and at a certain distance pulls on magnet B with a force of 100 N. The amount of force that magnet A exerts on magnet B is
exactly 100 N.
Compared to the huge force that attracts an iron tack to a strong magnet, the force that the tack exerts on the magnet is
equally huge.
Into which stable force field can a proton be placed at rest without being acted upon by a force?
magnetic field
The direction of the force exerted on a moving charge in a magnetic field is
at right angles to the direction of the motion.
The force on an electron moving in a magnetic field will be least when its direction is
the same as the magnetic field direction.
When an electron passes through the magnetic field of a horseshoe magnet, the electron's
direction is changed.
The force exerted on an electron moving in a magnetic field is maximum when the electron moves
perpendicular to the magnetic field.
The force a magnetic field exerts on a current-carrying wire is maximum when the wire is oriented
perpendicular to the magnetic field.
A current-carrying wire in a magnetic field
may be deflected.
may experience a force.
An electron beam directed through a magnetic field
may experience a force.
may be deflected.
No net force acts on a loop of wire in a magnetic field when
no current is in the loop.
no magnetic field lines pass through the loop.
If a magnet produces a force on a current-carrying wire, the wire
produces a force on the magnet.
A galvanometer indicates
a flow of electrons.
A galvanometer can be calibrated to measure
electric current.
electric voltage.
Although a magnet can change the direction of travel of an electron beam, it cannot change its
speed
kinetic energy.
Which force field can increase a moving electron's speed?
electric field
Which force field can accelerate an electron?
electric field
magnetic field
Over geologic history the Earth's magnetic field
has reversed direction many times.
Solar winds headed in Earth's direction are deviated mainly by
Earth's magnetic field.
The intensity of cosmic rays bombarding the Earth's surface is most at the
poles
Cosmic rays penetrate your body when
outdoors.
in mountainous regions.
safely in your home.
Earth's magnetic field is
protective to life on Earth.
Pigeons navigate primarily by
magnetic sensors in their heads.
