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Activity

Magnetic force field patterns

Summary: 
Students use iron filings to visualize the direction of the magnetic field lines and the shape of magnetic fields around various magnets. Can be used as a free experimentation activity. Can also be used to introduce magnetic field lines of the Sun.
Science content (2016 curriculum): 
Physics: Motion and Forces, Newton’s Laws, Gravity (K, 2, 6)
Science topic (2005 curriculum connection): 
Earth and Space Science: Stars and Planets (grade 3)
Physical Science: Force and Motion (grade 1)
image
Materials: 
  • various magnets (round, bar, fridge magnets)
  • iron filings sealed in a clear food container (e.g. salad/herb container) - use hot glue around the edges to seal, then shake to check for leaks; leave the white label on to show the patterns better. Alternatively, a large petri dish; attach a white label to the bottom to make the patterns show up better (though a thick label blocks some weak magnetic fields of fridge magnets)
Procedure: 

Before the class, prepare the iron filing container: sprinkle 1/4 teaspoon of iron filings into a larger salad container or 1/8 teaspoon into a small herb container. Apply a line of hot glue around the container edge and quickly seal shut. After a minute of cooling time, shake the iron filings around the sides of the container to locate any leaks, then seal these with more hot glue.

Each student experiments with moving magnets under the iron filings to see the patterns they make.
The shape of the magnetic field can be drawn with lines, that follow the lines that the iron filings make.

Discussion:
The patterns show how the force of the magnet spreads out around it.
Different magnets have different force field shapes.

For a lesson on the sun, this activity can be used to introduce how magnets have magnetic field lines around them.
The sun has very complex patterns of magnetic field lines, because of how the magnetic fields are formed within the sun:
Magnetic fields in the sun are made by the moving charged particles of the plasma particles which make up the sun. (Plasma is a fourth state of matter, more energetic than a gas, which exists in the very hot, high pressures of the sun).
The sun's plasma forms moving magnetic fields within the sun, which also loop outwards from it.
Show the field lines with this image: http://sdo.gsfc.nasa.gov/assets/gallery/print/Magnetic171.tif
The immense magnetic fields of the sun pull loops of gas from the sun and out along the field lines.
Amazing movie at: http://sdo.gsfc.nasa.gov/assets/gallery/movies/Magnetic_connection
and even more amazing close ups at: http://sdo.gsfc.nasa.gov/gallery/main/item/118 and http://sdo.gsfc.nasa.gov/assets/gallery/movies/Outburst304_sm.mov
Image of a prominence including the earth to scale: http://sdo.gsfc.nasa.gov/assets/gallery/preview/SDO_Earth_scale.jpg
The Sun’s magnetic field lines sometimes twist so much that they “snap”, sprawling prominences (hot loops of plasma) into space. The plasma that does escape streams away from the sun as solar winds, filling the heliosphere which extends beyond the solar system.

Sunspots (darker regions on the surface of the Sun) are caused by strong magnetic fields blocking heat from the centre of the sun.
Larger sunspots are larger than earth.

Grades tested: 
Gr K
Gr 1
Gr 2
Gr 4
Gr 5
Gr 6
Gr 7
Teacher: 
Donna Greening
Ingrid
Mari Matsuo
Monika Pilat
Phyllis Daly
Reid McInnes
Stephanie Monaghan
Teaching site: 
General Gordon Elementary
ingridscience afterschool
Simon Fraser Elementary
Strathcona Elementary