LESSONS: Magnetism

The majority of lesson ideas below require minimal resources other than the smartphone, and are relevant to introductory physics in high school and college. However, creative individuals are using smartphone science in more complex ways, with drones, engineering kits, and much more. Follow us on Twitter @PhysicsToolbox and see our Publications page for additional content.
Identifying Permanent Magnets

What kinds of common METALS can be permanent magnets?

Try This

People frequently confuse permanent magnets with non-magnetic materials that can be polarized by a nearby permanent magnet. 

 

Collect a number of metallic objects from around the house. Using the Magnetometer tool, determine which materials are magnetic and which materials are not. (Note: Because the phone produces a magnetic field itself, even non-magnetic materials moved near the mobile device might interfere with the field and given a false impression that the item is magnetic. For the best result, hold the object steady, and compare with the magnetic field recorded by the mobile device when no object is present).

 

Challenge Yourself

  • What kinds of metals seem to make up permanent magnets?

  • Can you ever get the mobile device to record a magnetic field of 0 in all directions? Why or why not?

Related Resources

Magnetic Field Intensity

What is the relationship between the MAGNETIC FIELD STRENGTH and the DISTANCE from a magnetic "point source"?

Try This

The strength of a magnetic field is dependent upon the distance between the sensor and the "point-source" of the magnet. Using the Magnetometer tool, record the magneti field at various distances away from a strong but small permanent magnet.

 

Challenge Yourself

  • Create a graph of Magnetic Field Strength vs. Distance from the magnet, and derive a mathematical expression for this relationship.

  • If there are any constants in this mathematical expression, explain their significance.

  • Try performing the same experiment above, but use a fairly large, strong bar magnet. How does the graph of the magnetic field strength compare to before? Why might the nature of the relationship be different?

 

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Magnetic Poles

Where are the POLES of a bar magnet? A horseshoe magnet? A spherical or irregular magnet?

Try This

Acquire a collection of regular and irregularly-shaped strong magnets. Use the Magnetometer tool to determine where the poles of the magnets are. You might be surprised to find where they are located!

 

Challenge Yourself

  • Using data from the surface of the magnet, attempt to sketch the magnetic fields lines produced by each type of magnet.

  • Acquire a refrigerator magnet. How does the magnetic field of the "front" face compare to the "back" face of the magnet? Where are its poles located?

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Earth's Magnetic Field

Which way does the EARTH's MAGNETIC FIELD point at my latitude and longitude?

Try This

Using the Magnetometer tool, determine the strength of the Earth's magnetic field in three dimensions. Using an understanding of vectors, determine the direction of the Earth's magnetic field. 

 

Challenge Yourself

  • Share magnetic field values with students across the globe, noting respective latitude and longitude values.

  • Create a vector array of magnetic field values to observe the Earth's whole gravitational field.

  • Collect data over time, and observe changes in the Earth's magnetic field due to solar activity.

 

Related Resources

Planetary Magnetism

What do magnetic fields look like around planets?

Try This

Using the Magna-AR setting that makes use of the magnetometer, accelerometer, and gyroscope, visualize the Earth's magnetic field and explore a model "Earth" and a model "Planet X." 

 

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Energy in Magnetic Fields and Solar Flares

Where does energy "go" when magnets and their fields interact?

Try This

Using the Magna-AR setting that makes use of the magnetometer, accelerometer, and gyroscope, visualize how fields change when magnetic poles are brought together. Read about the implications magnetic field energy has for how stars release energy into space.

 

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