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