Core Practical 12: Investigating Magnetic Fields
Aim of the experiment
- To investigate the magnetic field pattern for a permanent bar magnet and between two bar magnets
Equipment
Equipment List
| Equipment | Purpose |
| Two bar magnets | Produce a magnetic field which is plotted |
| Plotting compasses | Show the direction of the magnetic field at a given point |
| Paper | Plot the magnetic field pattern on this |
| Pencil | Plot the magnetic field pattern with this |
Method
Step 1:
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- Place the magnet on top of a piece of paper
- Draw a dot at one end of the magnet (near its corner)
Step 2:
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- Place a plotting compass next to the dot, so that one end of the needle of the compass points away from the dot
- Use a pencil to draw a new dot at the other side of the compass needle
Step 3:
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- Move the compass so that it points away from the new dot, and repeat the process above
Step 4:
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- Keep repeating the previous process until there is a chain of dots going from one end of the magnet to the other
- Then remove the compass, and link the dots using a smooth curve – this will be the magnetic field line
Step 5:
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- Repeat the whole process several times to create several other magnetic field lines
Step 6:
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- Repeat the whole process for two bar magnets placed 5 cm apart first facing the same pole then facing opposite poles
Analysis of results
- The magnetic field pattern for the single bar magnetic should look like this:
The magnetic field of a bar magnet plotted
- The magnetic field pattern for two bar magnets should look like this:
Magnetic field of two bar magnets interacting
Evaluating the experiment
- Make sure the pencil you use is sharp to provide a clear and accurate drawing of the field lines
- Read the marker on the compass from above and not at an angle
- Allow the compasses to settle for a couple of seconds before taking the reading
