Would a compass with unmagnetized needle work?
We know that the needle that is used in a compass is a permanently magnetized ferromagnetic material and commonly steel is used.
If we used an unmagnetized iron needle instead, would it still align with Earth's magnetic field lines? If yes, how?
magnetic-fields ferromagnetism
asked 3 hours ago
physicsguy19
731116
add a comment |
We know that the needle that is used in a compass is a permanently magnetized ferromagnetic material and commonly steel is used.
If we used an unmagnetized iron needle instead, would it still align with Earth's magnetic field lines? If yes, how?
magnetic-fields ferromagnetism
asked 3 hours ago
physicsguy19
731116
Why would you think “yes”?
– ZeroTheHero
3 hours ago
With the magnetic field of Earth no
– Alchimista
3 hours ago
@ZeroTheHero: Probably because they know that even an unmagnetised hunk of iron will still be attracted to a magnet, and they're applying this knowledge to a specific application of magnets.
– Sean
42 mins ago
add a comment |
We know that the needle that is used in a compass is a permanently magnetized ferromagnetic material and commonly steel is used.
If we used an unmagnetized iron needle instead, would it still align with Earth's magnetic field lines? If yes, how?
magnetic-fields ferromagnetism
asked 3 hours ago
physicsguy19
731116
We know that the needle that is used in a compass is a permanently magnetized ferromagnetic material and commonly steel is used.
If we used an unmagnetized iron needle instead, would it still align with Earth's magnetic field lines? If yes, how?
magnetic-fields ferromagnetism
magnetic-fields ferromagnetism
asked 3 hours ago
physicsguy19
731116
asked 3 hours ago
physicsguy19
731116
asked 3 hours ago
physicsguy19
731116
asked 3 hours ago
physicsguy19
731116
asked 3 hours ago
physicsguy19
731116
731116
Why would you think “yes”?
– ZeroTheHero
3 hours ago
With the magnetic field of Earth no
– Alchimista
3 hours ago
@ZeroTheHero: Probably because they know that even an unmagnetised hunk of iron will still be attracted to a magnet, and they're applying this knowledge to a specific application of magnets.
– Sean
42 mins ago
add a comment |
Why would you think “yes”?
– ZeroTheHero
3 hours ago
With the magnetic field of Earth no
– Alchimista
3 hours ago
@ZeroTheHero: Probably because they know that even an unmagnetised hunk of iron will still be attracted to a magnet, and they're applying this knowledge to a specific application of magnets.
– Sean
42 mins ago
Why would you think “yes”?
– ZeroTheHero
3 hours ago
Why would you think “yes”?
– ZeroTheHero
3 hours ago
With the magnetic field of Earth no
– Alchimista
3 hours ago
With the magnetic field of Earth no
– Alchimista
3 hours ago
@ZeroTheHero: Probably because they know that even an unmagnetised hunk of iron will still be attracted to a magnet, and they're applying this knowledge to a specific application of magnets.
– Sean
42 mins ago
@ZeroTheHero: Probably because they know that even an unmagnetised hunk of iron will still be attracted to a magnet, and they're applying this knowledge to a specific application of magnets.
– Sean
42 mins ago
add a comment |
2 Answers
2
active
oldest
votes
A magnetic dipole would be induced in the iron bar and the iron bar would try and align itself along the magnetic field lines because of the torque applied on it by the interaction of the induced dipole and the Earth’s magnetic field.
However since the torque which was applied on the iron bar would be very small the chances are that there would not be an alignment even if you waited a long time.
answered 2 hours ago
Farcher
47.4k33696
2
In the first paragraph, you seem to be assuming that the induced magnetization would be along the length of the bar, but I don't see any reason why that would be true. It could be in any random orientation relative to the bar's long dimension. The effect would then be that the bar would experience a torque that would tend to return it to whatever orientation it had when it was first able to be magnetized (e.g., at the time when the iron was first cooled below the Fermi temperature). You're then describing a bar that is magnetized, which is contrary to the question.
– Ben Crowell
53 mins ago
add a comment |
An unmagnetized needle made out of a permeable but not permanently magnetizable material will feel a force from the earth's field, but likely almost no torque about its center of mass. The force will be in the direction of the field's gradient, not in the direction of the field. The gradient of the earth's field is likely to be small and dominated by local irregularities.
Iron is not only permeable but also able to be permanently magnetized. Farcher's answer points out that the iron needle actually would tend to spontaneously become permanently magnetized by the earth's field when it was first exposed to the earth's field. However, there is no reason that this magnetization would be along the length of the bar. It could be in any random orientation relative to the bar's long dimension. The effect would then be that the bar would experience a torque that would tend to return it to whatever orientation it had with respect to the earth's field when it was first able to be magnetized (e.g., at the time when the iron was first cooled below the Fermi temperature). Of course we're now describing a bar that is magnetized, which is contrary to your question. That is, your question is contradictory because we can't actually have an unmagnetized iron needle exposed to the earth's field.
answered 3 hours ago
Ben Crowell
48.4k4151292
add a comment |
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2 Answers
2
active
oldest
votes
2 Answers
2
active
oldest
votes
active
oldest
votes
active
oldest
votes
A magnetic dipole would be induced in the iron bar and the iron bar would try and align itself along the magnetic field lines because of the torque applied on it by the interaction of the induced dipole and the Earth’s magnetic field.
However since the torque which was applied on the iron bar would be very small the chances are that there would not be an alignment even if you waited a long time.
answered 2 hours ago
Farcher
47.4k33696
2
In the first paragraph, you seem to be assuming that the induced magnetization would be along the length of the bar, but I don't see any reason why that would be true. It could be in any random orientation relative to the bar's long dimension. The effect would then be that the bar would experience a torque that would tend to return it to whatever orientation it had when it was first able to be magnetized (e.g., at the time when the iron was first cooled below the Fermi temperature). You're then describing a bar that is magnetized, which is contrary to the question.
– Ben Crowell
53 mins ago
add a comment |
A magnetic dipole would be induced in the iron bar and the iron bar would try and align itself along the magnetic field lines because of the torque applied on it by the interaction of the induced dipole and the Earth’s magnetic field.
However since the torque which was applied on the iron bar would be very small the chances are that there would not be an alignment even if you waited a long time.
answered 2 hours ago
Farcher
47.4k33696
2
In the first paragraph, you seem to be assuming that the induced magnetization would be along the length of the bar, but I don't see any reason why that would be true. It could be in any random orientation relative to the bar's long dimension. The effect would then be that the bar would experience a torque that would tend to return it to whatever orientation it had when it was first able to be magnetized (e.g., at the time when the iron was first cooled below the Fermi temperature). You're then describing a bar that is magnetized, which is contrary to the question.
– Ben Crowell
53 mins ago
add a comment |
A magnetic dipole would be induced in the iron bar and the iron bar would try and align itself along the magnetic field lines because of the torque applied on it by the interaction of the induced dipole and the Earth’s magnetic field.
However since the torque which was applied on the iron bar would be very small the chances are that there would not be an alignment even if you waited a long time.
answered 2 hours ago
Farcher
47.4k33696
A magnetic dipole would be induced in the iron bar and the iron bar would try and align itself along the magnetic field lines because of the torque applied on it by the interaction of the induced dipole and the Earth’s magnetic field.
However since the torque which was applied on the iron bar would be very small the chances are that there would not be an alignment even if you waited a long time.
answered 2 hours ago
Farcher
47.4k33696
answered 2 hours ago
Farcher
47.4k33696
answered 2 hours ago
Farcher
47.4k33696
answered 2 hours ago
Farcher
47.4k33696
47.4k33696
2
In the first paragraph, you seem to be assuming that the induced magnetization would be along the length of the bar, but I don't see any reason why that would be true. It could be in any random orientation relative to the bar's long dimension. The effect would then be that the bar would experience a torque that would tend to return it to whatever orientation it had when it was first able to be magnetized (e.g., at the time when the iron was first cooled below the Fermi temperature). You're then describing a bar that is magnetized, which is contrary to the question.
– Ben Crowell
53 mins ago
add a comment |
2
In the first paragraph, you seem to be assuming that the induced magnetization would be along the length of the bar, but I don't see any reason why that would be true. It could be in any random orientation relative to the bar's long dimension. The effect would then be that the bar would experience a torque that would tend to return it to whatever orientation it had when it was first able to be magnetized (e.g., at the time when the iron was first cooled below the Fermi temperature). You're then describing a bar that is magnetized, which is contrary to the question.
– Ben Crowell
53 mins ago
2
2
In the first paragraph, you seem to be assuming that the induced magnetization would be along the length of the bar, but I don't see any reason why that would be true. It could be in any random orientation relative to the bar's long dimension. The effect would then be that the bar would experience a torque that would tend to return it to whatever orientation it had when it was first able to be magnetized (e.g., at the time when the iron was first cooled below the Fermi temperature). You're then describing a bar that is magnetized, which is contrary to the question.
– Ben Crowell
53 mins ago
In the first paragraph, you seem to be assuming that the induced magnetization would be along the length of the bar, but I don't see any reason why that would be true. It could be in any random orientation relative to the bar's long dimension. The effect would then be that the bar would experience a torque that would tend to return it to whatever orientation it had when it was first able to be magnetized (e.g., at the time when the iron was first cooled below the Fermi temperature). You're then describing a bar that is magnetized, which is contrary to the question.
– Ben Crowell
53 mins ago
add a comment |
An unmagnetized needle made out of a permeable but not permanently magnetizable material will feel a force from the earth's field, but likely almost no torque about its center of mass. The force will be in the direction of the field's gradient, not in the direction of the field. The gradient of the earth's field is likely to be small and dominated by local irregularities.
Iron is not only permeable but also able to be permanently magnetized. Farcher's answer points out that the iron needle actually would tend to spontaneously become permanently magnetized by the earth's field when it was first exposed to the earth's field. However, there is no reason that this magnetization would be along the length of the bar. It could be in any random orientation relative to the bar's long dimension. The effect would then be that the bar would experience a torque that would tend to return it to whatever orientation it had with respect to the earth's field when it was first able to be magnetized (e.g., at the time when the iron was first cooled below the Fermi temperature). Of course we're now describing a bar that is magnetized, which is contrary to your question. That is, your question is contradictory because we can't actually have an unmagnetized iron needle exposed to the earth's field.
answered 3 hours ago
Ben Crowell
48.4k4151292
add a comment |
An unmagnetized needle made out of a permeable but not permanently magnetizable material will feel a force from the earth's field, but likely almost no torque about its center of mass. The force will be in the direction of the field's gradient, not in the direction of the field. The gradient of the earth's field is likely to be small and dominated by local irregularities.
Iron is not only permeable but also able to be permanently magnetized. Farcher's answer points out that the iron needle actually would tend to spontaneously become permanently magnetized by the earth's field when it was first exposed to the earth's field. However, there is no reason that this magnetization would be along the length of the bar. It could be in any random orientation relative to the bar's long dimension. The effect would then be that the bar would experience a torque that would tend to return it to whatever orientation it had with respect to the earth's field when it was first able to be magnetized (e.g., at the time when the iron was first cooled below the Fermi temperature). Of course we're now describing a bar that is magnetized, which is contrary to your question. That is, your question is contradictory because we can't actually have an unmagnetized iron needle exposed to the earth's field.
answered 3 hours ago
Ben Crowell
48.4k4151292
add a comment |
An unmagnetized needle made out of a permeable but not permanently magnetizable material will feel a force from the earth's field, but likely almost no torque about its center of mass. The force will be in the direction of the field's gradient, not in the direction of the field. The gradient of the earth's field is likely to be small and dominated by local irregularities.
Iron is not only permeable but also able to be permanently magnetized. Farcher's answer points out that the iron needle actually would tend to spontaneously become permanently magnetized by the earth's field when it was first exposed to the earth's field. However, there is no reason that this magnetization would be along the length of the bar. It could be in any random orientation relative to the bar's long dimension. The effect would then be that the bar would experience a torque that would tend to return it to whatever orientation it had with respect to the earth's field when it was first able to be magnetized (e.g., at the time when the iron was first cooled below the Fermi temperature). Of course we're now describing a bar that is magnetized, which is contrary to your question. That is, your question is contradictory because we can't actually have an unmagnetized iron needle exposed to the earth's field.
answered 3 hours ago
Ben Crowell
48.4k4151292
An unmagnetized needle made out of a permeable but not permanently magnetizable material will feel a force from the earth's field, but likely almost no torque about its center of mass. The force will be in the direction of the field's gradient, not in the direction of the field. The gradient of the earth's field is likely to be small and dominated by local irregularities.
Iron is not only permeable but also able to be permanently magnetized. Farcher's answer points out that the iron needle actually would tend to spontaneously become permanently magnetized by the earth's field when it was first exposed to the earth's field. However, there is no reason that this magnetization would be along the length of the bar. It could be in any random orientation relative to the bar's long dimension. The effect would then be that the bar would experience a torque that would tend to return it to whatever orientation it had with respect to the earth's field when it was first able to be magnetized (e.g., at the time when the iron was first cooled below the Fermi temperature). Of course we're now describing a bar that is magnetized, which is contrary to your question. That is, your question is contradictory because we can't actually have an unmagnetized iron needle exposed to the earth's field.
answered 3 hours ago
Ben Crowell
48.4k4151292
edited 50 mins ago
answered 3 hours ago
Ben Crowell
48.4k4151292
answered 3 hours ago
Ben Crowell
48.4k4151292
answered 3 hours ago
Ben Crowell
48.4k4151292
48.4k4151292
add a comment |
add a comment |
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Why would you think “yes”?
– ZeroTheHero
3 hours ago
With the magnetic field of Earth no
– Alchimista
3 hours ago
@ZeroTheHero: Probably because they know that even an unmagnetised hunk of iron will still be attracted to a magnet, and they're applying this knowledge to a specific application of magnets.
– Sean
42 mins ago