electromagnet and a bar magnet,,, what is the difference??

Question

for physics class

Answer 1

An electromagnet becomes magnetic only when electricity is passing through it. A bar magnet is naturally magnetic.

Answer 2

An electromagnet is simply some piece of iron or other ferrous material setup where a moving current may be wrapped around it (so you wrap the iron bar in electrical wiring) and then when you supply the electricity. You then get an electromagnet. When you shut off the electricity, it is no longer as magnetic (but it could still be a little magnetic). A bar magnet is simply the shape of a natural magnet (or even an electromagnet made of a straight iron bar) in the shape of a straight bar with the north and south poles at opposite ends.

Answer 3

You're comparing apples and oranges. A bar magnet is a permanent magnet shaped like a bar, and a horseshoe magnet is a permanent magnet shaped like a horseshoe.

I'm not a magnet expert, but I'll tell you what I know.

Take an insulated copper wire and coil it many times around a nail. Peel a little bit of insulation off each end of the wire and touch the uninsulated ends to the positive and negative ends of a battery. The nail is now an electromagnet. It will pick up other nails. Take away one end of the wire from the battery and it will no longer be an electromagnet. The nails it picked up will drop. It won't completely lose its magnetism, though. It will become a weak permanent magnet. Mechanics have a trick they use for retrieving parts that fall into places too small to reach with their hand. They take an insulated copper wire and wind it many times around a screwdriver. Then they touch the opposite ends of the wire to the positive and negative terminals of the car battery for a second or two. Then they take the copper wire off and the screwdriver is a weak permanent magnet, strong enough to pick up small parts.

Answer 4

An electromagnet uses an electric current to induce a magnetic field in a magnetically "soft" material, when the current is shut off the magnetic field also goes. A bar magnet is made of a magnetically "hard" material that is exposed to a strong electromagnetic field, the properties of the material allows it to retain the magnetic field indefinitely.

Answer 5

An electromagnet is only magnetic when electricity is flowing through it. An example is a fire door in a school or hospital. It stays open because of an electromagnet that the door is touching. When the fire alarm goes off, the power is cut to all these doors and they close automatically.

Answer 6

A bar magnet is simply a bar of steel that has been magnetized. An electromagnet generates a magnetic field when you apply electrical power to it.

Answer 7

Electromagnetism is the physics of the electromagnetic field; a field encompassing all of space which exerts a force on particles that possess the property of electric charge, and is in turn affected by the presence and motion of those particles.

Electric and magnetic fields
It is often convenient to understand the electromagnetic field in terms of two separate fields: the electric field and the magnetic field.

The electric field is produced by the presence of electrically charged particles, and causes the electric force. Electric force is the force observed as static electricity, and causes the flow of electric charge (electric current) in electrical conductors.

The magnetic field is produced by the motion of electric charges, i.e. electric current. The magnetic field causes the magnetic force associated with magnets.

The term "electromagnetism" comes from the fact that electrical and magnetic forces are involved simultaneously. A changing magnetic field produces an electric field (this is the phenomenon of electromagnetic induction, which provides for the operation of electrical generators, induction motors, and transformers). Similarly, a changing electric field generates a magnetic field. Because of this interdependence of the electric and magnetic fields, it makes sense to consider them as a single coherent entity — the electromagnetic field.

This unification, which was completed by James Clerk Maxwell, is one of the triumphs of 19th century physics. It had far-reaching consequences, one of which was the understanding of the nature of light. As it turns out, what is thought of as "light" is actually a propagating oscillatory disturbance in the electromagnetic field, i.e., an electromagnetic wave. Different frequencies of oscillation give rise to the different forms of electromagnetic radiation, from radio waves at the lowest frequencies, to visible light at intermediate frequencies, to gamma rays at the highest frequencies.

The theoretical implications of electromagnetism led to the development of special relativity by Albert Einstein in 1905.

and

A magnet is an object that has a magnetic field. It can be in the form of a permanent magnet or an electromagnet. Permanent magnets do not rely upon outside influences to generate their field. They occur naturally in some rocks, but can also be manufactured. Electromagnets rely upon electric current to generate a magnetic field - when the current increases, so does the field.

Properties of magnets
Magnets are attracted to, or repelled by, other materials. A material that is strongly attracted to a magnet is said to have a high permeability. Iron and steel are two examples of materials with very high permeability, and they are strongly attracted to magnets. Liquid oxygen is an example of something with a low permeability, and it is only weakly attracted to a magnetic field. Water has such a low permeability that it is actually slightly repelled by magnetic fields. Everything has a measurable permeability: people, gases, and even the vacuum of outer space.

The SI unit of magnetic field strength is the tesla, and the SI unit of total magnetic flux is the weber. 1 weber = 1 tesla flowing through 1 square meter, and is a very large amount of magnetic flux.

You could get more information from the 2 links below...

Answer 8

Bar magnet is a permanent magnet which is always magnetized

electromagnet is a conductor wrapped around iron core which is only magnetized when electrical current is applied

Answer 9

a bar magnet is made of either magnitite or has been magnitized by passsing it through a magnetic field.
an eletromagnet needs a energy source to make it work with a breaker switch to turn it on and off.

Answer 10

A. electro magnet is what they use at salvage yards to pick up heavy metallic loads and dump them elsewhere. b-wrong- electromags are strongest by far c-wrong- they both pick up iron fillings d-wrong - they both have magnetic fields