Paramagnetism

Definition

Paramagnetism is a form of magnetism that occurs in materials that are weakly attracted by an external magnetic field. Unlike ferromagnetic materials, paramagnetic substances do not retain their magnetic properties when the external field is removed, but they do have unpaired electrons that align with the magnetic field, resulting in a temporary magnetic moment. This alignment is typically only noticeable when an external magnetic field is applied, which influences the behavior of moving charges within the material.

5 Must Know Facts For Your Next Test

1. Paramagnetic materials, such as aluminum and oxygen, exhibit weak attraction to magnetic fields due to the presence of unpaired electrons.
2. The magnetic susceptibility of paramagnetic materials is positive but much smaller than that of ferromagnetic materials, indicating a much weaker response to magnetic fields.
3. Temperature plays a significant role in paramagnetism; as temperature increases, thermal agitation can disrupt the alignment of unpaired electrons, reducing the material's magnetic moment.
4. When subjected to a strong external magnetic field, paramagnetic materials can exhibit a measurable magnetization, which is temporary and disappears once the field is removed.
5. The phenomenon of paramagnetism can influence the behavior of charged particles within a material, affecting their motion and interactions with external magnetic fields.

Review Questions

• How does the presence of unpaired electrons in paramagnetic materials influence their behavior in an external magnetic field?
  • Unpaired electrons in paramagnetic materials create a scenario where these electrons can align with an external magnetic field. When the field is applied, these unpaired electrons orient themselves along the direction of the field, leading to a temporary increase in magnetization. However, once the external magnetic field is removed, the thermal agitation disrupts this alignment, causing the material to lose its magnetization.
• Compare and contrast paramagnetism and ferromagnetism regarding their properties and response to external magnetic fields.
  • While both paramagnetism and ferromagnetism involve materials responding to external magnetic fields, they differ significantly in strength and permanence. Paramagnetic materials only exhibit weak attraction and do not retain magnetization after the removal of the field due to random thermal motion disrupting electron alignment. In contrast, ferromagnetic materials can become strongly magnetized and maintain this magnetization even after the external field is removed due to cooperative alignment of atomic moments.
• Evaluate how temperature affects paramagnetism and discuss its implications for applications involving moving charges in electric and magnetic fields.
  • Temperature has a critical impact on paramagnetism since higher temperatures increase thermal agitation among particles. This agitation disrupts the alignment of unpaired electrons with an external magnetic field, leading to reduced magnetization. In applications involving moving charges in electric and magnetic fields, such temperature dependence can affect performance; for example, in sensing or imaging technologies where sensitivity to weak magnetic fields is necessary. Understanding this relationship allows for better design and optimization of devices relying on paramagnetic effects.

Related terms

Ferromagnetism: A type of magnetism where certain materials can become permanently magnetized due to the alignment of their atomic magnetic moments.

Diamagnetism: A form of magnetism that occurs in materials that are weakly repelled by a magnetic field and does not have any unpaired electrons.

Magnetic Moment: A vector quantity that represents the strength and direction of a magnetic source, often associated with the motion of electrons in atoms.