Temporary Magnet

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Magnet Science in Action

A temporary magnet is a magnet that remains magnetized for only a small time interval as compared to a permanent magnet. The materials that are used to make temporary magnets are usually soft materials that have low magnetic properties such as annealed iron or steel. What are temporary magnets? Temporary magnets take on the properties of a magnet if they are touching something magnetic. This happens when a paperclip becomes magnetic as it touches a permanent magnet. Things like wood or glass do not have the properties to become temporary magnets. Common temporary magnets include nails and paperclips, which can be picked up or moved by a strong magnet. Examples would be paperclips and nails and other soft iron items. The soft magnet is prepared by magnetic materials made by an alloy of cast iron and nickel. It is a temporary magnet.

Magnets are solid objects of stone, metal, or other material, which have the property of attracting iron-containing materials.

This attracting property is either natural, as in the case of lodestone, or induced (formed by unnatural means).

You can demonstrate the science of magnets at home, by producing and testing the strength of a magnetic field.

Magnet Science Projects

Project 1: What’s the Attraction?

All magnets have the ability to attract other magnets or magnetic objects (such as iron and some other metal objects). But a magnet doesn’t necessarily have to touch a magnetic object for the object to be attracted to it. Try this experiment to learn why.

What You Need:

  • Plastic or wooden ruler
  • Paperclip
  • Two or more different magnets
  • Notebook
  • Pencil

What You Do:

  • Line the paperclip up along the end of the ruler so that one side of the paperclip is at the ruler’s zero mark.
  • Place one magnet at the other end of the ruler. Now, hold the ruler in place with one hand and slowly slide the magnet toward the paperclip with your other hand. When the paperclip attaches to the magnet, stop moving the magnet.
  • Look at where the magnet was at along the ruler to see how far apart the magnet and paperclip were when they came together. (You might need to try it a few times before you are sure!) Write down the distance in your notebook. Draw a picture of the magnet that you used so you will remember which one it was.
  • Do steps 1-4 again with each of the magnets that you have.

What Happened:

All magnets have a magnetic field – an area around a magnet where its magnetism affects other objects. By measuring how far the magnet was from the paperclip when they become attached, you were finding the length of the magnetic field. Stronger magnets can generally attract magnetic materials from a farther distance than weaker magnets can. Based on that fact and the results you wrote in your notebook, which of your magnets was the strongest? Which one was weakest?

Project 2: Which Magnet Is the Strongest?

A good way to test how strong different magnets are is to see how many magnetic objects it can attract. Try this experiment with your magnets!

What You Need:

  • Several magnets
  • Box of paperclips
  • Notebook
  • Pencil
  • Someone to help you

What You Do:

  • Have your helper hold on to one end of one of the magnets. Stick one paperclip to the other end of the magnet. One end of the paperclip should dangle off the magnet. (Your magnet may be really strong, so you may need your helper to hold the paperclip so just an end is touching the magnet rather than the side of the paperclip, like in the picture.)
  • Now touch another paperclip to the end of the first paperclip to start a paperclip chain. Keep adding paperclips until no more stick to the chain. In your notebook, write down how many paperclips the magnet was able to hold together in a chain before paperclips started to fall off.
  • Do steps 1 & 2 with the other magnets, recording in your notebook how many paperclips would stick in a chain to each magnet.

What Happened:

When a magnet touches another magnetic object (such as a paperclip), the object becomes a temporary magnet for as long as it is touching the real magnet! It can now be used to pick up more paperclips.

Each additional paperclip also becomes a temporary magnet with a weaker magnetic force than the one before it. Some magnets may be able to hold a chain of five paperclips while another magnet may only be able to hold one or two paperclips.

How many paperclips a magnet can hold is a good indication of its strength. If you have a strong enough magnet and lift up the paperclips long enough, you may find that some of the paperclips will keep the ability to act like magnets for a little while even when they are not touching the magnet.

If this happens, you have just made a very strong temporary magnet.

Science Words

These words about magnets are used in the science projects. If you are not sure what they mean, just read the definitions below!

Magnetic object – any object that can be attracted to a magnet. Paperclips, iron filings, keys, and bobby pins are all examples of magnetic objects.

Magnetic field – an invisible area around a magnet where its magnetic force affects other objects. The magnetic field is what actually pulls other magnetic objects towards a magnet.

Temporary magnet – a magnetic object that can become a magnet when it is touching a permanent magnet but loses its magnetic properties when it is no longer touching the permanent magnet.

Magnet Science Lesson

Magnets in household items

A magnet is a solid object, usually a rock or piece of metal, that has the ability to attract certain materials.

To help discover what is and what is not attracted to magnets, go on a magnet hunt.

Look around the room and help your child make a list of objects he or she thinks will be attracted to the magnet as well as a list of objects that will not be attracted. After making your lists, test each of the objects.

(Don’t use magnets on computers, cassette tapes, discs, and other electronic devices – it could damage the magnets inside of them!)

Compare your results with what you predicted would be attracted. Were you correct on all your predictions? Were you wrong on any?

Discuss why items did or did not stick when you originally thought the opposite would be true.

For instance, the object is made out of plastic but coated with shiny paint to make it look metallic; not all metals are attracted to magnets; or maybe just parts of an object were attracted to the magnet. What does this tell us about magnetic attraction?

(That an object must be made out of metal to be attracted, but not all metals are attracted.)

Metals such as iron, nickel, and cobalt are attracted to magnets. Steel has iron in it, so it is also attracted to magnets.

Alternatively, you can use this coloring pageas part of a magnet hunt. Go around the house and find things that are magnetic. Circle the items on the coloring sheet that are attracted to the magnet and draw in any other items you found that are also magnetic.

As mentioned before, many common household items have magnets in them and are part of what makes these items work. Electronic devices such as refrigerators, washing machines, lamps, telephones, TVs, and stereos all have magnets in them.

Attraction and Repulsion

Temporary Magnet

All magnets have two ends where the pull is strongest – a north pole and a south pole. The poles are named this way because if a magnet is floating in water or is suspended by a string tied around its middle, it will align itself in a north-south direction, consistent with the magnetic field of the Earth.

To best show how the poles of magnets react with each other, get two bar magnets with the north poles and south poles labeled. Holding firmly onto the magnets, have your child try to push their hands and the ends of the magnets together so that the north poles of both magnets meet. What happens? Now flip one of the magnets around and try pushing the ends together so that a north pole of one magnet meets with the south pole of the other magnet. What happened this time? Finally, flip the other magnet so that the south poles are facing each other and try to push them together. What happened?

Children should find that when a north pole was facing a south pole, they felt a force pulling the magnets together. But when the north poles were facing each other or the south poles were facing each other, they should have felt a force pushing them apart. Help children understand that opposite poles attract (pull together) while similar poles repel (push apart).

Magnetic Field

The invisible area around a magnet which attracts another object is called a magnetic field.

Temporary Magnet And Permanent Magnet

Magnetic objects (such as paperclips) will get pulled towards the magnet if they are placed in this field. You can see the magnetic field of a magnet using iron metal filings in a Ziploc bag or iron filings in a sealed case.

(We highly recommend putting loose filings in a sealed bag to avoid a mess.)

Lay a bar magnet on a table. Gently shake the bag or case to evenly distribute the iron filings and lay it on top of the magnet.

(You may also want to try placing the magnet on top of the Ziploc bag.)

Observe the pattern of the iron filings. The magnetic field is strongest at the poles. You can see this because the iron filings cluster at these points.

Now place two bar magnets on the table with similar poles facing each other.

Temporary

Place them as close together as possible without them moving away from each other.

Place the iron filings on top of the magnets. Observe the pattern of the iron filings.

Now flip one magnet around so that opposite poles are facing each other and get them as close as possible without them moving together.

Place the iron filings on top and again observe the pattern made.

In each of these experiments, the iron filings allow us to visibly see how the magnetic field is shaped and how multiple magnetic fields can interact with each other.

Extend this by trying different magnet shapes (ring magnet, horseshoe magnet, etc.) to see what their magnetic fields look like. Also try it with multiple magnets close together to see how their magnetic fields interact with each other.

Adult supervision should always be provided when children are playing with magnets.

More Physics & Engineering:

Main Difference – Permanent vs. Temporary Magnets

Magnets are an extremely important part of our daily lives. Magnets are used in door-catchers and to stick notes on to fridge doors, but often, unbeknown to us, most of the magnets that surround us are in electric circuits in the form of electromagnets. The type of magnets on fridge doors are permanent magnets while the magnets which are used to make electromagnets are typically temporary magnets. The main difference between permanent and temporary magnets is that permanent magnets do not require an external magnetic field in order to stay magnetized whereas, temporary magnets remain magnetized only as long as there is a strong external magnetic field around them.

What are Permanent Magnets

Permanent magnets are magnets that retain their magnetism over long periods of time. Permanent magnets are made of hard ferromagnetic materials. They can be magnetised by placing them inside an external magnetic field. Ferromagnetic materials display hysteresis: when the external magnetic field is gradually reversed, the material resists demagnetization over a longer range of external magnetic field strengths. This is summarized in the magnetization curve below:

The horizontal axis gives the size of the external magnetic field, the vertical axis gives the magnetization. Note that when the external magnetic field increases around (follow the bottom curve), the magnetization of the material increases rapidly. When the external magnetic field is reversed (the top curve), the magnetization does not reduce significantly over a larger range of reduced or reversed magnetic fields. This behaviour is typical for a hard ferromagnetic material. Hard ferromagnetic materials include aluminium, cobalt, and steel.

What are Temporary Magnets

Temporary magnets can be also magnetized by placing them inside an external magnetic field. The material’s magnetism lasts so long as the external magnetic field is switched on, and disappears when the external magnetic field disappears. Temporary magnetic materials include both paramagnets and soft ferromagnets.

How Are Temporary Magnets Made

Atoms that make up paramagnetic materials do not have their magnetic moments aligned with each other. When they are placed inside an external magnetic field, the magnetic moments of the atoms line up with the external magnetic field, magnetizing the material. Ferromagnetic materials are different from paramagnetic materials in that their magnetization is spontaneous (their magnetization increases rapidly as the external magnetic field is increased over a narrow range).

Soft ferromagnetic materials also show hysteresis: however, their hysteresis loops tend to be much narrower than those of hard ferromagnetic materials, meaning soft ferromagnetic materials lose their magnetization much more easily when the external magnetic field is reduced. However, they are still different from paramagnetic materials in that they magnetize spontaneously.

Soft ferromagnetic materials, such as soft iron, are useful for the construction of devices that do not require permanent magnets. In transformers, when current flows in coils wound around the soft iron “core”, the core becomes magnetized and conducts the magnetic field to the other coil in the transformer. In order to produce an alternating current, the direction of the magnetic field through the core needs to change periodically. This is very difficult to achieve if the core had been made of a permanent magnetic material. In some applications that utilize powerful magnetic fields (MRI machines, for example) it is important that the magnets can be switched off (see the video below!)

Difference Between Permanent and Temporary Magnets

Dependence of Magnetization on the Presence of an External Field

Temporary Magnets Are Often

Permanent magnets can be magnetized by putting them in an external magnetic field. They do not lose their magnetization over a large range of reverse external magnetic fields, or when the external magnetic field is switched off.

Temporary Magnet

Temporary magnetscan also be magnetized by putting the material inside an external magnetic field. When the external magnetic field is switched off, the material loses its magnetization.

Type of Material

Permanent magnetic materials are so-called hard ferromagnetic materials.

Temporary magnetic materials are paramagnetic or soft ferromagnetic materials.

Image Courtesy

Temporary Magnet Definition Science

“The main hysteresis loop and initial magnetization curve calculated using Stoner-Wohlfarth theory for an isotropic system of identical single-domain magnets.” by RockMagnetist (Own work) [CC0 1.0], via Wikimedia Commons