What is the main difference between electric charges and magnetic poles?
electric charges can be isolated, magnetic poles cannot be isolated
electric charges cannot be isolated, magnetic poles can be isolated
electric charges both attract and repel, magnetic poles only attract
electric charges both attract and repel, magnetic poles only repel
What is the basic source of magnetism?
Charged particles alone
Movement of charged particles
Magnetic dipoles
Magnetic domains
When looking at iron filings that have been allowed to interact with a magnetic field, what does the density of lines suggest?
that the magnetic field is weakest there
that the magnetic field is strongest there
that the electric field is un-canceled there
that the electric field is the strongest there
Why are most materials not magnetic?
they do not conduct electricity
they are not metals
the magnetic fields produced by the electron spin is canceled
they are insulators, meaning that electrons are not free to move around in the atomic lattice
How is each piece when a bar magnet is broken in two?
as magnetic as the original magnet
actually stronger than the original magnet
half as strong as the original magnet
no longer magnetic.
The induced voltage across a stationary conductor in a stationary magnetic field is
zero
reversed in polarity
increased
decreased
All pieces of iron have magnetic domains, why are most iron nails not magnetic?
they cannot conduct electricity
their domains are all oriented with respect to magnetic poles
their domains are randomly oriented, canceling out most magnetic forces
their atoms contain 4 electrons that spin magnetism is un-cancelled
The induced voltage across a coil with 250 turns that is located in a magnetic field that is changing at a rate of 8 Wb/s is
1000V
2000 V
31.25V
3125V
The ability of a material to remain magnetized after removal of the magnetizing force is known as
permeability
reluctance
hysteresis
retentivity
Find out an example for dia-magnetic materials.
super conductors
alkali metals
ferrites
transition metals
