1. Investigate magnetic field direction.
Work with a partner. Place a bar magnet on a white sheet of paper. Pour a very small amount of filings onto the paper. The filings should form lines. Determine the direction of the lines by placing a compass on the lines and drawing an arrow to show which direction is north on the compass. After drawing a few of the arrows, label which end of the magnet represents north and which represents south.
2. Get ready to create ferrofluids.
One way we can observe magnetic fields is through the use of a material called ferrofluid. A ferrofluid is a liquid that becomes strongly magnetized in the presence of a magnetic field. In this activity, you will create ferrofluids and observe their behavior. Gather all the materials you’ll need. As you move through the steps with your partner, document your observations in the worksheet Ferrofluid Observations.
3. Measure the filings or toner.
Use the graduated cylinder to measure 15 milliliters (mL) of filings or toner. Pour the toner into the beaker. Record the amount on the data collection sheet.
4. Measure and add the oil.
Use the graduated cylinder to measure and add 15 mL of oil into the beaker. Record the amount on the data collection sheet. Use a stirrer to mix thoroughly.
5. Check and adjust the ferrofluid mixture.
Check the mixture by placing a magnet on the outside of the beaker to see how the mixture performs. Your mixture is working well if you see fairly defined spikes form when you hold the magnet to the outside of the beaker. If that does not happen, adjust the mixture by adding more filings/toner or oil. Continue adjusting your mixture until you are satisfied with the results. Make sure to measure and record materials added and to mix thoroughly between additions. Record your observations.
6. Complete the worksheet.
Pour the mixture into a 2-liter bottle preform or a petri dish. If using a petri dish, put the dish into a sealable sandwich bag to protect from accidental spillage. Have paper towels on hand in case of leaks. Hold the magnet directly on the side of the preform and gather the ferrofluids to the magnet. Slowly pull the magnet away from the preform. Repeat the process 3 or 4 times. Measure the distance between the perform and the magnet in centimeters and document your observations in Part 2 of Ferrofluid Observations. If possible, include sketches with your written observations.
7. Make connections to planetary magnetic fields.
What similarities and differences did you observe between the behavior of the filings and the ferrofluids? Write a brief paragraph comparing the two on the back of your worksheet. Notice that the ferrofluid spikes appear to have equal distances and look like they would continue around to the opposite end of the magnet from one pole to the other, demonstrating the same “lines” as observed with the filings due to the polarity of the magnets. The liquid suspension holds the filings back. The filings not suspended in a liquid will form magnetic lines from one pole of the magnet to the other. This same phenomenon happens to magnetic fields on Earth and other planets. Magnetic fields serve as a shield that protects planets from solar radiation. The solar particles are deflected to the polar regions along the magnetic field lines. If a planet has very little or no magnetic field, there is not enough protection for people or vehicles exploring that planet.
What is a ferrofluid?
Materials You Provide
- 2-liter bottle preforms (optional)
- Bar or earth magnets
- Fine metal filings or magnetic laser printer toner
- Magnetic compasses
- Mineral oil
- Paper towels
- Plastic petri dishes
- Safety goggles
- Sealable plastic sandwich bags
- Tablespoons or graduated cylinders
- White paper
The resources are also available at the top of the page.
Magnetic poles are assigned the labels of north or south. Magnetic fields can be described via the concept of magnetic lines of force; the lines form closed loops originating at the North Pole and ending at the South Pole and also passing through the material. The space where the lines of force are crowded represents a region of strong magnetic field compared to the region where the lines are farther apart. Magnetic field lines are an important tool for describing the nature of magnetic interactions. A rule for describing interactions between magnetic poles is that like poles repel and unlike poles attract. Hard magnetic materials are permanent magnets and they either attract (south-north) or repel (south-south). Ferrofluid is soft magnetic material. A soft magnetic material, versus a hard magnetic material, is always attracted to a permanent magnet independent of its polarity. Magnetic fields help protect planets and their inhabitants from solar radiation.
Term Part of Speech Definition Encyclopedic Entry cardinal direction Noun
one of the four main points of a compass: north, east, south, west.
fluid that becomes magnetized in the presence of a magnetic field.
magnetic field Noun
area around and affected by a magnet or charged particle.
(nT) unit of measurement for magnetic flux density (magnetic field B), which is magnetic force on a moving charge.
north magnetic pole Noun
constantly moving area where compass needles point from all over the Earth.
property of having or being attracted to poles, such as positive and negative electrical charges.
solar radiation Noun
light and heat from the sun.
solar storm Noun
sudden change in the Earth's magnetosphere, caused by the solar wind interacting with the Earth's magnetic field. Also called a geomagnetic storm.
south magnetic pole Noun
constantly moving area where south compass needles point from all over the Earth.
space weather Noun
changes in the environment outside the Earth's atmosphere, usually influenced by the sun.
For Further Exploration