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Permanent Magnets and Electromagnets

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  • Last Updated : 03 Sep, 2021

The magnetic field and strength are the main differences between permanent magnets and electromagnets. A wire-wound coil creates the magnetic field in an Electromagnet, whereas the magnetic field of a Permanent (Bar) Magnet cannot be altered. The strength of a Permanent Magnet is determined by the material used in its construction, but the strength of an Electromagnet is determined by the passage of electric current through it. Ceramic magnets, flexible magnets, Neodymium iron boron magnets, and Samarium cobalt magnets are the four types of permanent (bar) magnets. Each one has its own set of uses and kinds. 

Let’s look at the distinctions between a permanent magnet and an electromagnet in greater detail.

Permanent Magnet

These magnets have the ability to keep their magnetism and magnetic characteristics for a longer period of time. Permanent magnets are made up of strongly magnetic hard materials. The Bar Magnet is an excellent example of a permanent magnet. This magnet shows the behaviour of magnets in great detail. Permanent magnets are also known as Bar Magnets.

Types of Permanent Magnets

The many types of permanent magnets will be discussed in this section. They are as follows:

  1. Ceramic magnets: They are the most cost-effective permanent magnets available. We utilise them in the food processing industry, as well as in magnetic resonance imaging and other fields.
  2. Flexible Magnets: They are utilised in refrigerator door seals. Rubber polymers, plastics, and magnetic powders can all be used to create them.
  3. NdFeB (Neodymium Iron Boron Magnet): These are rare earth magnets. It’s fairly simple to oxidise. It’s a high-priced substance. It’s frequently used in jewellery making, bookbinding, and other crafts.
  4. Magnet made of samarium cobalt (SmCo): These are also rare earth magnets. It is temperature and oxidation resistant. They have a stronger magnetic field. They can be used in high-end motors, turbomachinery, and other applications.

Application of Permanent Magnets

  • Hard drives, motors, vehicles, generators, TVs, phones, headphones, speakers, transducers, and sensors all require permanent magnets. A magnet’s most common purpose is to attract other magnetic things, but it also serves a variety of tasks in electrical devices.
  • The majority of speakers use a permanent magnet that interacts with a wire coil (an electromagnet, really). The audio signal travels along the cable and causes the speaker to move. The speaker creates sound by moving air.
  • Magnetic hooks or closures are frequently found on cabinets or other furniture doors. Typically, they are manufactured using a cheap ceramic magnet sandwiched between two steel plates that attract and touch a steel “strike plate” on the door.

Disadvantages of Permanent Magnets

  • A permanent magnet’s magnetic field can only be created below a particular temperature. As a result, these magnets aren’t suitable for use in hot-device applications.
  • With time, these permanent magnets deteriorate. As a result, the maximum magnetic field’s intensity is lowered. The permanent magnet’s poles cannot be changed.

Electromagnet

The device acts as a magnet when a battery is linked to a solenoid (a coil of wire coiled around a nail). The magnetic field created by the current flowing through the coil is responsible for this. The magnetism of the nail lasts as long as there is currently running through the coil; if there is no current, the magnetism of the nail is lost. When you wind a coil of wire around an iron core, you can make electromagnets.

Types of Electromagnets

Electromagnets are classified as resistive, superconductors, or hybrids.

  1. Resistant electromagnets: This sort of magnet uses copper wires to create a magnetic field. The magnetic field is created when the copper wire is twisted around a piece of iron and an electric current is sent through the copper wire. The stronger the field, the more copper wires are twisted.
  2. Hybrid electromagnets: They are a mix of the two types of electromagnets mentioned above, resistive and superconductor electromagnets.
  3. Superconductor magnets: They are made of superconductive metal, which has no resistance to current flow. The same approach is used to create superconductor magnets. The temperature of the copper coil is lowered using liquid nitrogen or liquid helium in these electromagnets. The low temperature separates the copper atoms from the current flow, resulting in a high magnetic field. Even when the power is cut off, these electromagnets continue to function.

Application of Electromagnets

  • Electromagnets are the most frequent type of magnet used in transformers. When you feed electricity to the transformer, the coils create changing magnetic fields. This causes a voltage to be generated. Transformers are generally employed in the electric power system to manage alternative voltages.
  • You may get the desired voltage whenever you want. We can achieve this by altering the current flow. Electromagnets can also be used in magnetic locks, relays, magnetic levitation, electric bells, and loudspeakers, among other things.

Disadvantages of Electromagnets

  • Copper connections are required in a vast number of electromagnets. As a result, they are unsuitable for usage in compact areas. They also need a lot of upkeep. The electromagnet may be damaged by the short-circuit.
  • Electromagnets require a constant current source. Due to numerous variables such as ohmic heating, inductive voltage spikes, core losses, coil coupling, and so on, this may impact the magnets and their field at some point in the future.

Difference between Permanent Magnet and Electromagnet

The difference between a permanent magnet and an electromagnet is as follows:

  • Permanent magnets are permanently magnetized while electromagnets are temporarily magnetized.
  • The former is made up of hard materials while the latter one is made up of soft materials.
  • The magnetic field line’s intensity is fixed, i.e. it cannot be changed in permanent magnets while the magnetic field lines’ strength may be adjusted to suit our needs in electromagnets.
  • The poles are fixed in the former one while the poles can be varied in the latter one.

Similarities between Permanent Magnets and Electromagnets

Both magnets have fictitious magnetic field lines. Magnets have north and south poles, and their behaviour is determined by the earth’s geographic north and south poles. The characteristics of magnetism are present in both magnets.

Sample Questions

Question 1: Why does soft iron use as an electromagnet?

Answer:

When the current flows, the soft iron inside the coil becomes a magnet, which strengthens the magnetic field. Because soft iron loses its magnetic as soon as the current stops flowing, it is a good choice.

Question 2: Why do manufacturers use steel to make permanent magnets?

Answer:

Steel is an iron and carbon alloy. Steel is not magnetic in its native form, but it may be converted to become magnetic. When a nonmagnetic piece of steel is placed near a magnet, the atoms within it rearrange in such a way that a permanent magnet is formed. As the atoms align, a magnetic field is created that maintains its intensity. The atoms of an item must be appropriately aligned in order to produce a magnetic field. Because of the inherent arrangement of its atoms, steel is extremely useful for this purpose.

Question 3: What is the difference between a permanent magnet and an electromagnet?

Answer:

A permanent magnet is a material item that becomes magnetised and generates its own magnetic field. On the other hand, when an electric current is allowed to flow through a coil of wire, it functions as a magnet called electromagnet.

Question 4: What benefits does an electromagnet have over a permanent magnet?

Answer:

The major advantage of electromagnets is that they can control their magnetic pull intensity by turning the magnet on or off and changing the current. They also have a stronger draw than permanent magnets. According to some estimations, the biggest electromagnet is 20 times more powerful than the most powerful permanent magnet.

Question 5: What is the purpose of a magnet?

Answer:

Electric generators utilise magnets to generate electricity, while electric motors use magnets to convert electrical energy into mechanical energy. Speakers, electric bells, maglev trains, TV and computer displays, cellphones, refrigerators, and other electronic devices utilise it.

Question 6: What are the advantages of electromagnets over permanent magnets?

Answer:

Permanent magnets are more expensive. Electromagnets are less expensive. This is due to the lower cost of the materials used in the electromagnet. An Electromagnet’s magnetic strength may be adjusted to suit your needs. In the event of a permanent magnet, this is not feasible.


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