Magnetic Field of a Bar Magnet

Figure 1

A bar magnet is a seemingly ordinary piece of metal that induces a magnetic field in its vicinity.

This magnetic field affects any magnetic material that lies within it.

In this experiment you will explore the nature of the magnetic field that surrounds a bar magnet.

einstein™Tablet+ with MiLAB or Android /iOS Tablet with MiLAB and einstein™LabMate Magnetic Field sensor Bar magnet Ruler (nonmetallic) Clear tape

1.

Launch MiLAB (

2.

Connect the Magnetic Field sensor sensor to one of the ports on the einstein™Tablet+ or einstein™LabMate.

Set the sensor switch to the low sensitivity range.

Tape the ruler to the Tabletop using clear tape.

Place the bar magnet parallel to the ruler so that the ruler extends at least 4 cm past the magnet on either side (see Figure 1). This will enable you to map the magnetic field 4 cm distance from the magnet.

Use the pull down menu in the Sensor Control Panel to select the Magnetic Field sensor.

Make sure that only the Magnetic Field sensor is selected.

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Program the sensor to log data according to the following setup: Magnetic Field Sensor

Magnetic 10 mT (mT)

Rate:

50/sec

Duration:

5 Sec

1.

Position the edge of the magnetic probe on the zero mark of the ruler. Make sure that the probe is perpendicular to the ruler.

2.

Tap Run (

3.

Save your data after each measurement by tapping Save (

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5.

Tap Run ( ) on the main toolbar to record the magnetic field’s strength at the 0 cm mark.

Now position the edge of the magnetic probe at the 1 cm mark of the ruler, keeping the probe

6.

perpendicular to the ruler, then tap Run ( ) to record the magnetic field’s strength at the 1 cm mark.

Move the sensor along the ruler at 1 cm intervals. Each time take a reading by tapping Run (

) each time you wish to record a data sample and record the value in your notebook. ) on the main toolbar.

) until you have reached a point 4 cm beyond the other end of the bar magnet.

For more information on working with graphs see: Working with Graphs in MiLAB. Consider the data in your notebook and answer the following questions: 1. What was the strongest positive magnetic field around the bar magnet?

2. Where on the bar magnet did you measure the strongest positive magnetic field?

3. What was the strongest negative magnetic field around the bar magnet?

4. Where on the bar magnet did you measure the strongest negative magnetic field?

5. Where on the bar magnet did you measure zero magnetic field?

6. What can you infer from the fact that the magnetic field around a bar magnet has both positive and negative values? Will two bar magnets attract or repel each other?

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Explore the magnetic field of a pair of bar magnets.

Explore the magnetic field of a horseshoe (U-shaped) magnet.