Field Directions Around a Bar Magnet, Oscilloscope Demonstration, Magnetic Forces and Electric Currents, Forces in a Curved Wire

Field Directions Around a Bar Magnet

A compass was placed around a bar magnet and the magnetic field lines were marked.  It can be seen that the magnetic field runs from the positive (North) to the negative (south).  

Also, if you pour iron over the bar magnet they form around the magnet in the shape of the field lines which ran from the north to south pole.

Gauss’s Law for Electric Charge

You cant have only one pole in the imaginary surface, you must have both poles enclosed therefore the net flux is always zero.

Oscilloscope Demonstration

We observed the effects of a magnetic field on an electron and we determined that the way the electron is moving is perpendicular to the direction of the magnetic field and when the magnetic field approaches the electron parallel then there is no effect.

The right hand rule can be used to find the direction of the force, current, or magnetic field where the thumb is the force, the finger is the current and the middle finger is the magnetic field.

Magnetic Forces and Electric Currents

We observed the effects that a magnet had on a non magnetic wire that carries  a current using Lorentz force.  The way we initially had the circuit set up the wire jumped up because of the direction of the magnetic field and the current going through the wire.  We reversed the current through the wire and the wire now gets pulled down.  

magnet being pushed up

magnet being pushed down

Forces in a Curved Wire

A spread sheet was used to find the using Lorentz force I*dL*B*sin(theta) and the forces were summed up to find the total force on the section of the curved wire which we found to be .70 N