Download Lab - Magnetism and Magnetic Fields

Magnetism and Magnetic Fields
Name(s): ________________________ ________________________
Use materials from the class to explore the following: Make sure to complete record your answers on a SEPARATE piece of
paper, then compile then on a word document and hand them in next class.
1. Use the bar magnet to find out which materials are "magnetic" (i.e. are attracted to the bar magnet).
a. Test some different materials and make a table listing the materials that are magnetic and those that
are not.
b. Are the magnetic materials attracted to one pole or both poles of the bar magnet? Materials that are
strongly magnetic are called ferromagnetic.
2. Using 2 bar magnets compare the forces between like poles and unlike poles.
a. Describe how like poles and unlike poles interact with one another.
b. How are magnetic fields generated from permanent bar magnets different from magnetic fields
generated from electromagnets (generated when a current is passed through a wire)?
3. Use a bar magnet to find the N & S poles of a compass.
a. How do you know the compass is also a permanent magnet?
b. Now place the compass away from the bar magnets. Once it has settled down, it will point in one
direction. (Note: you might need to leave the classroom to get an accurate reading!) Explain why it
does this.
c. What is the origin of the terms "north pole" and "south pole" for the ends of magnets? Collect a some
string from your teacher and use it to suspend one of the bar magnets. Will it also become aligned
like a compass?
4. Ceramic magnets are made of a composite of iron oxide and barium or strontium carbonate. Use a compass to
determine the N & S poles of the stack of 3-4 ceramic magnets (the larger flat sides are the poles). Remove
one magnet from the stack.
a. Do the remaining magnets still have the same N & S poles? How about 2 magnets? 1 magnet?
b. Based on your observations, can the poles of a permanent magnet separated into N & S "monopoles?"
(a monopole is a single north or south pole). In other words can you ever have just a North pole, or
just a South pole. Explain.
5. As with gravitational and electric forces, scientists visualize magnetic forces by mapping magnetic fields.
Magnetic field lines can be draw to indicate the direction and strength of the magnetic force field. We are
going to map the magnetic field of a bar magnet. The direction of the magnetic field is defined as the direction
that the north pole of a compass points when it is in that field.
a. Make a drawing of a bar magnet, labeling the N & S poles. Place a compass at the different position
shown below, and then draw the direction of the N pole of the compass needle using an arrow to
indicate the direction of the external magnetic field.
b. To get another view of magnetic field lines, you can use iron filings. If you sprinkle these on a piece of
paper that is lying on a magnet, they will become magnetized and line up with the field. Make a sketch
of what this looks like.
6. Create a simple circuit, with a battery and a resistor using 2 wires. Lay one of the wires over the compass,
parallel to the compass needle.
a. Connect the power supply, and notice what happens to the compass needle.
b. Record what happens when you increase the voltage (which also increases the current)?
c. Disconnect the circuit and switch leads that are connected to the battery. What happens to the
compass needle when you switch the direction of the current?
Analysis
1. Electric fields are invisible. How can we tell if there is an electric field present in a region of space? (What
can you use to measure the size and direction of an electric field?) Magnetic fields are also invisible. How can
we tell if there is a magnetic field present in a region of space?
2. What is the source of magnetism/magnetic fields? (Hint: you might need to do some research about the atomic
structure of element; specifically Iron, Nickel and Cobalt. Maybe even ask Mr. Franco!)
3. The diagram below shows a small bar magnet that is suspended from a string so it is free to move. What will it
do if it is placed in the strong magnetic field pictured at the right? (Ignore any other magnetic fields)
4. Why is it useful (for scientists & engineers) to understand magnetic fields? (A very important question we
should be constantly asking our teachers and ourselves!) List some ways magnets and electromagnets are
used in industry.