A magnet is something that usually attracts magnetic metals such as iron to itself.  We also discovered that a magnet has two

poles.  The North Pole and the south pole. We then examined the path of the magnetic field lines.  A bar magnet was placed

under a sheet of paper, and then iron filings were poured on the paper.  It was noticed that the filings were aligned in the

path of the magnetic field.  The field generated from the North Pole into the South Pole.  This experiment was first performed

by Descartes in he course of his study of the mapping process of magnets.

It was also discovered that the filings were more concentrated at the poles of the magnet.  We also used a compass to further

our study.  It was noticed that the compass points north.  This is because it is reacting to the earth's magnetic field.  It points

north because the earth's northern magnetic pole is actually South Pole and the earth's southern magnetic pole is a North

Pole.  When a compass was brought near a North Pole, its needle was moved away indicating repulsion.  When the compass

was brought towards a South Pole the needle moved quickly towards it indicating an attraction.  It was therefore concluded

that like poles repel each other while unlike poles attract.  We then tried to make a magnet that had only one pole.  The

magnet that we used for this experiment was made up of two magnets joined together. We separated the two a bar magnet to

see whether the northern pole would remain as a single pole and the south remain as a single pole.  We discovered that the

separated magnets still were dipoles. We then moved our attention the a current carrying wire.
 
 

Ampere was the person who found the relationship between electricity and current.  This relationis known as the Right Hand

Current Rule. The Right Hand Current Rule basically says that if the thumb is pointed in the direction of the current, the

direction of the magnetic field, anywhere in the surrounding, is given by the direction of the fingers curling around the wire at

that location.  Ampere had shown that the magnetic force experienced by a compass needle in the vicinity of a current carrying

straight wire acted at right angles to the current along a series of concentric circles.

We performed another experiment in which current was passed though a wire.  We used a compass to detect the magnet field.

We discovered that the magnetic field was circular around the current carrying wire.

 

Ampere furthered his study on the current carrying wires by the conductor into a loop to find out what happens when curent

pass through a loop.  We then proceeded in the spirit of Ampere to investigate the current in loops.  It was noticed that the

field inside the coil was stronger than the field outside and that the direction of the magnetic field in the coil was

perpendicular to the plane of the coil. This was exactly what Ampere discovered!
 
 

We used the right hand rule to determine the direction of the magnetic field.  It is interesting to note that vibration of the

magnetic fields together with electrical fields give light its wave properties.  For further details about light, check out Chilumba

Mubashi's experiment on the Photoelectric Effect.   Using the right hand rule, we also determined the direction of the magnetic

force, the magnetic field and the direction of velocity for a moving charge (q).  We discovered that the force was perpendicular

to the velocity, and perpendicular to the field.  Because the force is perpendicular to the velocity, it is a deflecting force.  This

means that the force changes the direction of velocity without altering the velocity.  It also means that direction of motion of the

charge motion follows a circular path.

With this background knowledge, we then proceeded to study the magnetic deflection of electrons and the charge to mass

ratio.  The magnetic deflection was first of all derived mathematically. The magnetic force on an electron traveling with

velocity v perpendicular to magnetic field B:

Since the electron’s motion path is circular, the magnetic force can be equated to the centripetal force FC = mv2/r .

evB = mv2/r .

One of the equipment used for this study was a special vacuum, which is equipped with an electron gun that fires electrons

towards a graticle.   The graticle or phosphor screen is supported at an angle so that the electron path could be visible.  The

other equipment used for this study were two coils in a Helmhotlz configuration.  The Helmholtz configuration is made up of

two coils separated by a distance equal to the radius of the coils.  The coils were used to provide the magnetic field.  The

electron gun in the tube gets its energy from a high voltage.  The magnetic field causes the electron to follow a circular path.

For several values of gun voltage (V), the Helmholtz current was adjusted so that the electron beam passed through the

coordinates (x,y) = (12+ 2.4).  For each value of V, the average of the two currents I- and I+ was calculated.  The average

calculated current was used to calculate the magnetic field B and the ratio e/m
 
 

Where B = 

Our calculated e/m ratio waswhile the value found in HECHT was .  The experimental

errorwas 48.04%.  This was a very significant error.  The source of this error was a systematic  error.  The magnetic field was

very strong at the center of the two coils, but at the edges of the coils, the magnetic field was zero because the fields from

each coil canceled each other.  In our calculation of B, this effect was not taken into consideration, hence greater value of B

was obtained which significantly decreased the e/m ratio.