Magnetism (3, Review). Like poles repel Unlike poles attract.
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Transcript of Magnetism (3, Review). Like poles repel Unlike poles attract.
Magnetism (3, Review)
Like poles repel
Unlike poles attract
Magnetic Field Lines vs. Electric Field Lines
Magnetic Dipole Electric Dipole
What happens when you bring a compass near a bar magnet?
The north indicator of the compass will point toward the south pole of a magnet.
This is also why a compass points north, it's lining up with the earth's magnetic poles.
Source of Magnetic Fields• Electrical Charge in motion.
– Currents occur at the atomic level in atoms due to the orbits of electrons around the nucleus.
– The intrinsic spin (+1/2, -1/2) is critical in the case of magnetism.
Moving Charges in a magnetic Field
•Magnetic fields cause moving charges to curve
•http://homepages.ius.edu/kforinas/physlets/magnetism/magnetH.html
•http://www.youtube.com/watch?v=thtrYYoI7AM
Field around a wire• http://www.launc.tased.edu.au/online/
sciences/physics/Lenz%27s.html
• Demo!
Lenz’s Law• http://www.launc.tased.edu.au/online/
sciences/physics/Lenz%27s.html
• Demo!
Questions•Describe the forces acting on this floating magnet
Questions•What are the vector and non-vector quantities related to magnetism?
Questions•Draw bar magnets and field lines as follows:
•N-N
•N-S
•S-S
Questions•:Draw a horseshoe magnet
QuestionsDraw a wire with a current
•Show the field lines
QuestionsAdd compasses to all drawings above
http://www.magnet.fsu.edu/education/tutorials/index.html
Questions•How do you produce a magnetic field?
•Describe the forces acting on this floating magnet
•What are the vector and non-vector quantities related to magnetism?
•Draw bar magnets and field lines as follows:
•N-N
•N-S
•S-S
•Draw a horseshoe magnet
•Draw a wire with a current
•Show the field lines
Add compasses to all drawings above
http://www.magnet.fsu.edu/education/tutorials/index.html
Questions•Draw a wire moving through a magnetic field
•What is equation?
•Show direction of induced current
Questions•Draw a wire moving through a magnetic field
•What is equation?
•Show direction of induced current
•EMF
Questions
•Draw a wire with a current in a magnetic field
•What is equation?
•What are the forces acting on the wire?
Questions
•Draw a beam of protons moving through a magnetic field
•What is equation?
•Show the forces
•What if the velocity is increased?
Questions•Draw a wire moving through a magnetic field
•What is equation?
•EMF
•Show direction of induced current
•Draw a wire with a current in a magnetic field
•What is equation?
•What are the forces acting on the wire?
•Draw a beam of protons moving through a magnetic field
•What is equation?
•Show the forces
•What if the velocity is increased?
Questions•Draw a wire in a magnetic field
•Show the direction to produce maximum potential difference
•Show a direction to produce no potential difference