Magnetic materials—paramagnetism: Identify the correct statement about the existence and interaction of permanent magnetic dipoles in paramagnetic substances.

Introduction / Context:
Paramagnetism describes the magnetic behavior of materials whose atoms or ions possess permanent magnetic dipole moments (usually from unpaired electron spins) but do not spontaneously order as in ferromagnets. Understanding whether dipoles exist and how strongly they interact is fundamental in materials science, solid-state physics, and electrical engineering applications such as magnetic sensing and cryogenics.

Given Data / Assumptions:

• Room or moderate temperatures are considered (far from magnetic ordering transitions).
• Weak external magnetic fields so that linear susceptibility applies.
• Polycrystalline or gaseous paramagnets without strong exchange coupling.

Concept / Approach:

In paramagnets, individual atoms or ions carry permanent dipole moments. However, thermal agitation randomizes orientations, and there is negligible exchange interaction between neighboring moments. When an external field is applied, a small net alignment occurs, producing a positive susceptibility typically following Curie or Curie–Weiss law (χ ≈ C/T or C/(T − θ) with small θ). The absence of strong mutual interaction distinguishes paramagnets from ferro- or antiferromagnets, where exchange forces are strong and lead to collective order.

Step-by-Step Solution:

Verification / Alternative check:

Empirically, magnetization M in paramagnets is proportional to H/T (Langevin or Brillouin functions), consistent with independent dipoles weakly aligned by the field and randomized by temperature, confirming negligible inter-dipole coupling.

Why Other Options Are Wrong:

• “Dipoles do not exist” contradicts the positive susceptibility and microscopic origin of paramagnetism.
• “Very strong interaction” would imply ferro/antiferromagnetic ordering.
• “May or may not exist” is vague and ignores the defining presence of moments in paramagnets.
• “Only at very low temperatures” is incorrect; paramagnetism occurs broadly until ordering temperatures are approached.

Common Pitfalls:

• Confusing paramagnetism (independent dipoles) with ferromagnetism (collective order) because both yield positive χ.

Final Answer:

permanent magnetic dipoles exist but the interaction between neighbouring dipoles is negligible