# Shared Flashcard Set

## Details

Chapter 24
Magnetism
39
Physics
05/06/2013

Term
 What is the cause of magnetism?
Definition
 the movement of charge
Term
 What are the three degress of magnetism?
Definition
 ferromagnetic--strongly attracted; paramagnetic--slightly attracted; diamagnetic--slightly repelled
Term
 Why is iron ferromagnetic?
Definition
 unpaired electron spins line up parallel with each other forming domains
Term
 What is the curie point?
Definition
 temperature above which a ferromagnetic material stops being ferrogmagnetic
Term
 What is a magnetic field? How are the field lines drawn?
Definition
 the area around a magnet or moving charge in which a force is felt; field lines drawn from north to south
Term
 What happens to the strength of the field as the number of field lines increases?
Definition
 the field strength increases
Term
 What is a domain?
Definition
 microsocopic area within a ferromagnetic material in which the atoms are magnetically alligned
Term
 Who is Hans Oersted?
Definition
 high school teacher that discovered the link between electricity and magnetism
Term
 Who is Andre Ampere?
Definition
 he came up with the hand rules
Term
 What did Michael Faraday and Joseph Henry do?
Definition
 they discovered electromagnetic induction
Term
 What is Ampere's Rule for the Straight conductor (first hand rule)?
Definition
 current-right hand; electrons-left hand; thumb always points away from the current
Term
 How do you make an electromagnet? What are the three factors that affect the strength of an electromagnet?
Definition
 you need wire, a ferromagnetic material to wrap it on, and a battery; 3 factors--how many wraps, type of core, and current
Term
 How do you use Ampere's Rule for a soelnoid to determine the N-pole of an electromagnet?
Definition
Term
 What is the motor effect?
Definition
 a current-carrying wire placed in a magnetic field will move
Term
 How do you calculate the force exerted on a current carrying wire in a magnetic field?
Definition
 F=BIl
Term
 HOw do you calculaethe foce exerted on a harge moving in a magnetic field?
Definition
 F=qvB
Term
 What are the three parts of the motor?
Definition
 armature, magnets, connection
Term
 What type of energy conversion occurs in an electric motor?
Definition
 converts electricity to motion
Term
 Who discovered electromagnetic induction?
Definition
Term
 What is electromagnetic induction?What three factors affect how much current is produced in electromagnetic induction?
Definition
 production of voltage across a conductor through a magnetic field; speed, strength, and number of turns
Term
 HOw do yo9u fetermine the EMF produced by a wire being moved in a magnetic field?
Definition
 EMF=Blv
Term
 What is the main application of electromagnetic induction?
Definition
 the generator
Term
 What is the difference in an ACgenerator and a DC generator?
Definition
 AC generator has 2 slip rings; DC generator uses a split ring commutator
Term
 HOw are motors and generators similiar and how are they different?
Definition
 they have the same parts; motor converst electrical to mechanical; generator converts mechanical to electrical
Term
 What is Lenz's law?
Definition
 the induced current is always in the direction to oppose the motion that caused it
Term
 What is back EMf and how is it produced?
Definition
 caused by the generator action of a motor
Term
 What is inductance?
Definition
 a changing current in a coil of wire is going to produce a changing magnetic field
Term
 What is self inductance?
Definition
 the inductance of EMF in a wire carrying a changing current
Term
 What is mutual inductance?
Definition
 effect in which a changing current through a trasnformer's primary coil creates a changing magnetic field, which is carried through the core to the transformers secondary coil, where the changing field induces a varying EMF
Term
 How does a transformer work?
Definition
 application of mutual inductance
Term
 What is the differnce in a step up transformer and a step down transformer?
Definition
 step up-steps up the voltage; step-down--steps down the voltage
Term
 Where does the Earth's magnetic field come from?
Definition
 comes from inside the Earth; convection currents of molten material generates the field
Term
 Why is the EArth's magnetic field important to life?
Definition
Term
 What is the aurora borealis?
Definition
 where teh particles from the sun hit our atmosphere
Term
 What are some uses of magnetism in today's world?
Definition
 motors, generators, refrigerator magnets
Term
 What hand do you use with current? electrons?
Definition
 current, right hand. electrons, left hand
Term
 what is beta?
Definition
 magnetic field strength, how many lines per area (tesla)
Term
 What is flux?
Definition
 the way of counting the field lines (webers)
Term
 Magnets are made of what kind of material?
Definition
 ferromagnetic
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