International Baccalaureate Internal Assessment in Physics HL
Topic: Investigation of the relationship between the temperature of a magnet and its magnetic field
strength.
Research question: How does increasing temperature (193K, 243K, 293K, 393K, 423K) of a magnet
affect its magnetic field strength (μT)?
Personal code: gyz166 Session: May 2019
I declare that this work is my own work and is the final version. I have acknowledged each use of the
words or ideas of another person, whether written, oral or visual
1. Introduction
The magnetism in IB Physics curriculum is mainly discussed with omitting the underlying causes of it.
However, the forces due to magnets or the effects caused by them are made clear. On the other hand the
factors affecting magnets are not included in the curriculum. As paper by Cheng (2014) shows, one of
such factors is temperature. This fact is used in research on superconducting electromagnets (Boebinger
et al., 2017). However, as temperatures needed to demonstrate such effects are unreachable in household
setting (close to absolute zero (Dixon,2014)) this internal assessment will focus on the permanent
magnets. It aims at investigating the effect of range of temperatures on their strength. Also, as only a
small range of temperatures may be safely achieved at home, a mathematical model will be used to
further investigate the relationship between magnetic field strength and the temperature of magnet.
2. Research question: How does increasing temperature (193K, 243K, 293K, 393K, 423K) of a
magnet affect its magnetic field strength (μT)?
3. Background information
3.1 Types of magnets
The main types of magnets are permanent and electromagnets(Courses.lumenlearning.com, n.d.). The
latter are formed by coiling current-carrying wire around core made of soft ferromagnetic material e.g.
iron (Tsokos, 2014). The permanent ones on the other hand have intrinsic magnetic properties and they
divide into multiple subgroups but the one of interest for this internal assessment is that of ferrimagnets.
1
, Their magnetic properties arise due to unequal magnetic strength of magnetic domains (Spaldin, 2010).
This mechanism will be explained in the next section.
3.2 Magnetism
The magnetic properties arise due to arrangement of electrons in electron shells and subsequent
arrangement of atoms in lattice (Pierzchalska, 1972). When the electron shells of atoms are not full then
the atoms align themselves due to electromagnetic forces, forming domains. Within these domains the
unpaired electrons create net magnetic field in one direction (Giancoli, 2005). However, there are
numerous such domains in the material and they tend to align in anti-parallel to each other thus
cancelling-out their individual magnetic fields. In case when the domains have varying magnitudes of
magnetic field strength then there is possibility of creating net magnetic field thus making the material
a ferrimagnet. The most common ones are magnetite and nickel (Néel, 1948).
3.3 Effect of temperatures on magnets
In solid materials the attractive forces between atoms are so strong that they oscillate about fixed
positions in an array called crystal lattice (Giancoli, 2005). With increasing temperature the frequency
of oscillations intensifies. Because of that, in magnets, the alignment of the paired electrons is disturbed
and so it affects the net magnetic field produced by the material (Van.physics.illinois.edu, 2007). When
material reaches Curie point its permanent magnetic properties are lost and a metal may be turned into
magnet only by magnetization (Buschow, 2001). The reason is that the arrangement of atoms is broken
as the magnitude of oscillations of atoms increases as the material is heated up (Giancoli, 2005). On the
other hand, when temperature decreases the motion of atoms slows down and the alignments are more
stable thus strengthening the net magnetic field. In order to measure the percentage change of the
strength of magnetic field with temperature, the reversible temperature coefficient (RTC) is used. Its
unit is %K-1 and it gives information about how much the magnetic field changes as a function of
temperature (Constantinides, 2010).
2
Topic: Investigation of the relationship between the temperature of a magnet and its magnetic field
strength.
Research question: How does increasing temperature (193K, 243K, 293K, 393K, 423K) of a magnet
affect its magnetic field strength (μT)?
Personal code: gyz166 Session: May 2019
I declare that this work is my own work and is the final version. I have acknowledged each use of the
words or ideas of another person, whether written, oral or visual
1. Introduction
The magnetism in IB Physics curriculum is mainly discussed with omitting the underlying causes of it.
However, the forces due to magnets or the effects caused by them are made clear. On the other hand the
factors affecting magnets are not included in the curriculum. As paper by Cheng (2014) shows, one of
such factors is temperature. This fact is used in research on superconducting electromagnets (Boebinger
et al., 2017). However, as temperatures needed to demonstrate such effects are unreachable in household
setting (close to absolute zero (Dixon,2014)) this internal assessment will focus on the permanent
magnets. It aims at investigating the effect of range of temperatures on their strength. Also, as only a
small range of temperatures may be safely achieved at home, a mathematical model will be used to
further investigate the relationship between magnetic field strength and the temperature of magnet.
2. Research question: How does increasing temperature (193K, 243K, 293K, 393K, 423K) of a
magnet affect its magnetic field strength (μT)?
3. Background information
3.1 Types of magnets
The main types of magnets are permanent and electromagnets(Courses.lumenlearning.com, n.d.). The
latter are formed by coiling current-carrying wire around core made of soft ferromagnetic material e.g.
iron (Tsokos, 2014). The permanent ones on the other hand have intrinsic magnetic properties and they
divide into multiple subgroups but the one of interest for this internal assessment is that of ferrimagnets.
1
, Their magnetic properties arise due to unequal magnetic strength of magnetic domains (Spaldin, 2010).
This mechanism will be explained in the next section.
3.2 Magnetism
The magnetic properties arise due to arrangement of electrons in electron shells and subsequent
arrangement of atoms in lattice (Pierzchalska, 1972). When the electron shells of atoms are not full then
the atoms align themselves due to electromagnetic forces, forming domains. Within these domains the
unpaired electrons create net magnetic field in one direction (Giancoli, 2005). However, there are
numerous such domains in the material and they tend to align in anti-parallel to each other thus
cancelling-out their individual magnetic fields. In case when the domains have varying magnitudes of
magnetic field strength then there is possibility of creating net magnetic field thus making the material
a ferrimagnet. The most common ones are magnetite and nickel (Néel, 1948).
3.3 Effect of temperatures on magnets
In solid materials the attractive forces between atoms are so strong that they oscillate about fixed
positions in an array called crystal lattice (Giancoli, 2005). With increasing temperature the frequency
of oscillations intensifies. Because of that, in magnets, the alignment of the paired electrons is disturbed
and so it affects the net magnetic field produced by the material (Van.physics.illinois.edu, 2007). When
material reaches Curie point its permanent magnetic properties are lost and a metal may be turned into
magnet only by magnetization (Buschow, 2001). The reason is that the arrangement of atoms is broken
as the magnitude of oscillations of atoms increases as the material is heated up (Giancoli, 2005). On the
other hand, when temperature decreases the motion of atoms slows down and the alignments are more
stable thus strengthening the net magnetic field. In order to measure the percentage change of the
strength of magnetic field with temperature, the reversible temperature coefficient (RTC) is used. Its
unit is %K-1 and it gives information about how much the magnetic field changes as a function of
temperature (Constantinides, 2010).
2
