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| 184_notes:mag_interaction [2021/03/18 16:13] – [New Interaction] bartonmo | 184_notes:mag_interaction [2021/03/18 16:16] (current) – [Magnetic Field] bartonmo |
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| We will be focusing on describing and understanding the magnetic field, which is a [[184_notes:pc_efield#What_is_a_field|vector field]] that can be produced by a [[184_notes:perm_mag|permanent magnet]] (like a fridge magnet), [[184_notes:moving_q|a single moving charge]], or by an [[184_notes:b_current|electric current]] (many moving charges). Since it is a vector field, this means that the magnetic field has //both a magnitude and a direction//. | We will be focusing on describing and understanding the magnetic field, which is a [[184_notes:pc_efield#What_is_a_field|vector field]] that can be produced by a [[184_notes:perm_mag|permanent magnet]] (like a fridge magnet), [[184_notes:moving_q|a single moving charge]], or by an [[184_notes:b_current|electric current]] (many moving charges). Since it is a vector field, this means that the magnetic field has //both a magnitude and a direction//. |
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| As $m$ is already used for mass, we represent the magnetic field by a $\vec{B}$. Because we use B as the letter variable, you may see books (or instructors) shorten "magnetic field" to just a "B-field". The SI units for magnetic field are given typically in "teslas" (named for [[https://en.wikipedia.org/wiki/Nikola_Tesla|Nikola Tesla]]) and abbreviated with a "T". A 1 T field is a very large magnetic field. For comparison, the Earth's magnetic field is about $32*10^{-6}$ T, a refrigerator magnet has a magnetic field of about $0.005 T$, and a MRI (magnetic resonance imaging) machine has a magnetic field of $1-5$ T. [[https://www.youtube.com/watch?v=6BBx8BwLhqg|As you can see in this video]], a 4 T B-field is capable of producing huge amounts of force and can move large objects like chairs or oxygen tanks across the room. The largest (sustained) magnetic field that we have produced on Earth is about 45 T. Larger magnetic field exist in extraterrestrial situations such as stars, galaxies, and black holes. But, if you come across a situation with a magnetic field that is larger than about 45 T, it probably is not realistic or, at a minimum, it is not occurring on Earth. | As $m$ is already used for mass, we represent the magnetic field by a $\vec{B}$. Because we use B as the letter variable, you may see books (or instructors) shorten "magnetic field" to just a "B-field". The SI units for magnetic field are given typically in "teslas" (named for [[https://en.wikipedia.org/wiki/Nikola_Tesla|Nikola Tesla]]) and abbreviated with a "T".** A 1 T field is a very large magnetic field.** For comparison, the Earth's magnetic field is about $32*10^{-6}$ T, a refrigerator magnet has a magnetic field of about $0.005 T$, and a MRI (magnetic resonance imaging) machine has a magnetic field of $1-5$ T. [[https://www.youtube.com/watch?v=6BBx8BwLhqg|As you can see in this video]], a 4 T B-field is capable of producing huge amounts of force and can move large objects like chairs or oxygen tanks across the room. The largest (sustained) magnetic field that we have produced on Earth is about 45 T. Larger magnetic field exist in extraterrestrial situations such as stars, galaxies, and black holes. But, if you come across a situation with a magnetic field that is larger than about 45 T, it probably is not realistic or, at a minimum, it is not occurring on Earth. |
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| Because a telsa is such a large magnetic field, you may sometimes come across a magnetic field given in units of "gauss" or "G" (named after [[https://en.wikipedia.org/wiki/Carl_Friedrich_Gauss|Carl Gauss]]), where $1T=10,000G$. However, since teslas are the SI unit, we will be working with those. | Because a telsa is such a large magnetic field, you may sometimes come across a magnetic field given in units of "gauss" or "G" (named after [[https://en.wikipedia.org/wiki/Carl_Friedrich_Gauss|Carl Gauss]]), where $1T=10,000G$. However, since teslas are the SI unit, we will be working with those. |
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| The rest of the notes in this week will go into more detail about what the magnetic field looks like and how we can calculate the magnitude/direction for the various sources of magnetic fields. | The rest of the notes in this week will go into more detail about what the magnetic field looks like and how we can calculate the magnitude/direction for the various sources of magnetic fields. |