PHYSICS 101-1 Unit 2 Lesson 1 Flashcards
Electromagnetic Induction
Inducing an electromotive Force (emf/voltage) into a conductor as it cuts magnetic lines of Force
Magnetism
property of a magnet that permits it to attract other things magnetic
Magnetic Field
zone of influence surrounding a magnet
summation of the fields of all magnetic domains
Permeability
also known as magnetic susceptibility and it says how easily something can be magnetized
Magnetic Retentively
ability to stay magnetized
What are the types of magnets?
natural magnets
artificial permanent magnets
electromagnets
Natural Magnets
made by nature
what is the largest natural magnet ?
earth
What is an example of a natural magnet?
lordestone
What does lordestone consist of ?
iron oxide or magnetite
Artificial Permanent Magnets
usually shaped like a bar or horseshoe
Alnico
alloy of aluminum, nickel, and cobalt that can made into a strong magnet
Electromagnetics
temporary magnets made by electric current
What are the 3 fundamental laws of magnetism ?
- magnetic poles
- repulsion-attraction
- inverse square law
Magnetic Poles
magnets have a north and south pole on opposite ends and even when broken these qualities remain true
Repulsion-Attraction
repulsion- like ends repel
attraction- opposite ends attract
Inverse square law
force between two magnetic fields directly proportional to the product of magnetic pole strengths divided by the square of the distance between them.
If the distance between two bar magnets is halved, the magnetic force between the 2 bar magnets increase by _____the original strength.
4 times
Electron Spin
electrons spin on their axis while orbiting the nucleus
Magnetic fields are always made when an ______ ______ is in motion
electrical charge
Electrons tend to spin in ______
pairs
Theory of Magnetism
spinning electrons have a magnetic field.
If the electrons are unbalanced in an atom, there will be a ____ _____.
net field
Magnetic Domains
An accumulation of many atomic magnets with their dipoles aligned.
Atoms that have an ___ # electrons in any shell exhibit a small magnetic field.
odd
The small magnet made by the electron orbit is called the _____ ______ or atomic magnets
magnetic dipole
When electrons are paired , the electrons will spin in opposite directions , causing the magnetic fields to _____ ____ each other.
cancel out
What are the 4 classifications of magnetic material?
Ferromagnetic
Paramagnetic
non-magnetic
Diamagnetic
Ferromagnetic Materials
“Simply Magnetic”
Includes Fe , Co , and Ni
Highly permeable
Highly susceptible to induction
Paramagnetic Materials
Low permeability
Weak attraction to magnetic fields
Example: platinum and aluminum
MRI contrast agents are usually paramagnetic
Nonmagnetic Materials
Not affected by magnetic fields and cannot be magnetized
Examples : Wood, glass, and rubber
Diamagnetic Materials
Weakly repelled by either magnetic pole
Cannot be artificially magnetized
Are not attracted to a magnet
Examples : water and plastic
Beryllium , bismuth , and lead weakly repelled by all magnetic fields
Electromagnetism
Refers to its relationships between electricity and magnetism
Electromagnet
A current-carrying cool of wire wrapped around an iron core that intensified the induced magnetic field
Conductor
Material that allows heat or electricity to flow
Magnetic Field
The Force fields made when magnetic dipoles arrange to make a magnet. The movement of a charged particle makes a magnetic field perpendicular to the motion of the particle.
The lines seen in a magnetic field are also called….
The lines of Force or flux
A magnetic field always surrounds a __________ in which an electric current is flowing.
Conductor
A ______ ________ surrounds any stream of charges particles, whether in a metallic conductor or in space.
Magnetic field
The ________ the current flow, the greater the restyling magnetic field.
Greater
The pattern of the magnetic field surrounding is in the shape of a _________ ________ _________ ________.
Series of concentric cylinders
“Right-Hand (Thumb) Rule” for a straight conductor:
The magnetic flux created around a current carrying conductor has a definite ______ and ________
direction and polarity
“Right-Hand (Thumb) Rule” for a straight conductor:
When a conductor is grasped with the right hand with the thumb pointing in the direction of _______ ______ , the fingers encircling the wire will indicate the direction of the ______ ______ ______ ______ around the current.
current flow , magnetic lines of force
Solenoid
a helix coil where current is flowing; it uses the coil loops to make a strong magnetic field
When a _________ is looped to make a coil, the magnetic fields from both sides join to _______ the magnetic field strength inside the loop.
conductor , double
When current flows in a “helix” there’s a north and south pole on the ________. With the right hand rule we can predict the direction of the ______ _______ in the coil and what end is the ______ pole.
magnet , magnetic flux ,north
If the coil is grabbed with the right hand where the fingers point in the direction of the ______ ______ , the extended thumb will point in the direction of the _______ pole.
current flow , north
Faraday’s Law: 4 factors that determine _____ _____ _____ _____ ______ cut per second by the conductor.
or the ______ _______ _______ ________
number of lines of force
flux linkages per second
Faraday’s Law
- speed of motion between lines of force and the conductor
- the strength of the magnetic field
- the angle between the conductor and the magnetic field
* **closer to 90 degrees spaces between lines of force grow smaller, more flux lines cut, bigger EMF - the induced EMF is directly proportional to the number of turns in the coil
What are the 2 types of induction?
mutual and self-induction
Mutual Induction
current flow from a primary coil passes through a secondary coil
Self-induction
occurs in direct current only
occurs continually in alternating current
using ferromagnetic coil would increase the self-inductance of the coil
Lenz’s Law
induced current will flow in a direction that opposes the action that induces it
*north of magnet attracted to north of conductor
Right Hand Rule for Induced electric current Direction
Hold the thumb and first two fingers of the right hand spread out.
Let the index finger point in the direction of the ______ _______, and the thumb point in the direction the conductor is __________. The middle finger will then point in the direction of the ________.
magnetic flux / field , moving , current
Direction of Induced Electric Current
depends on the relationship between the motion of the conductor and the magnetic field
To induce a current with the use of a magnetic field , the field cant be ______, but must be changing.
-says Faraday
constant
review the picture for faradays law right before test
okay
what are the 3 ways to create motion between the lines of force and the conductor?
- move the conductor through a stationary, unchanging field
- move magnetic lines of force through a stationary conductor with an unchanging strength magnetic field
- vary the magnetic flux-strength from a stationary magnet through a stationary conductor. as the flux strength varies the lines of force expand and contract to cause motion for current
If all the magnetic domains in an object are _________ , it acts like a magnet.
Aligned
A solenoid is basically the loops around a conductor and when this is iron what happens with the magnetic field ?
It gets strong af