What is the fundamental cause of diamagnetism?

Diamagnetism fundamentally arises from the orbital motion of electrons within atoms. When an external magnetic field is applied, it induces a change in the angular velocity of these orbiting electrons. This change, in accordance with Lenz's Law, generates an induced magnetic moment that is always directed opposite to the applied external magnetic field. This induced moment is temporary and is the sole source of magnetism in purely diamagnetic materials.

Why are diamagnetic materials weakly repelled by magnets?

Diamagnetic materials are weakly repelled because the induced magnetic moment within them is always oriented opposite to the direction of the external magnetic field. This opposition creates a repulsive interaction between the material and the external magnet. In a non-uniform magnetic field, this repulsion causes the material to move from regions of stronger field to regions of weaker field.

Is diamagnetism dependent on temperature?

No, diamagnetism is largely independent of temperature. The induced magnetic moment responsible for diamagnetism originates from the fundamental orbital motion of electrons, which is not significantly affected by thermal agitation or temperature changes. This is a key distinguishing feature from paramagnetism and ferromagnetism, which are temperature-dependent.

What is magnetic susceptibility for diamagnetic materials?

For diamagnetic materials, the magnetic susceptibility ($chi$) is small and negative. It typically ranges from $-10^{-5}$ to $-10^{-9}$. A negative susceptibility indicates that the induced magnetization within the material is in the opposite direction to the applied external magnetic field, leading to repulsion.

Can all materials exhibit diamagnetism?

Yes, diamagnetism is a universal property of all matter because all atoms contain orbiting electrons. However, in many materials, this weak diamagnetic effect is masked by stronger magnetic properties like paramagnetism (due to unpaired electron spins) or ferromagnetism (due to strong cooperative alignment of spins). Materials are classified as 'diamagnetic' only when diamagnetism is their dominant magnetic behavior.

Give some common examples of diamagnetic materials.

Common examples of diamagnetic materials include water (H$_2$O), copper (Cu), bismuth (Bi), gold (Au), silver (Ag), nitrogen gas (N$_2$), hydrogen gas (H$_2$), noble gases like helium (He) and neon (Ne), and most organic compounds. Superconductors are also perfect diamagnets, exhibiting the Meissner effect where they completely expel magnetic fields.

Diamagnetism

Physics

NEET UG

Version 1Updated 22 Mar 2026

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Diamagnetism is a fundamental property of all matter, though often overshadowed by other forms of magnetism. It arises from the orbital motion of electrons within atoms. When an external magnetic field is applied to a diamagnetic material, it induces a change in the orbital motion of these electrons. According to Lenz's Law, this change generates an induced magnetic moment that opposes the applied…

Quick Summary

Diamagnetism is a fundamental magnetic property present in all materials, though it is often weak and masked by other magnetic effects. It originates from the orbital motion of electrons within atoms.

When an external magnetic field is applied, it induces a change in the electron's orbital motion, which, by Lenz's Law, creates an induced magnetic moment that *opposes* the external field. This results in diamagnetic materials being weakly repelled by magnets.

Key characteristics include a small, negative magnetic susceptibility ( $chi < 0$ ), relative permeability slightly less than 1 ( $mu_r < 1$ ), and independence from temperature. The induced magnetization is temporary and disappears when the external field is removed.

Examples include water, copper, bismuth, and noble gases. Understanding diamagnetism is crucial for distinguishing it from paramagnetism and ferromagnetism in NEET.

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Key Concepts

Origin of Induced Magnetic Moment

In atoms, electrons orbit the nucleus, creating tiny current loops. Each loop has an orbital magnetic moment.…

Behavior in a Non-Uniform Magnetic Field

A key characteristic of diamagnetic materials is their behavior in a non-uniform magnetic field. Due to the…

Magnetic Susceptibility and Relative Permeability

Magnetic susceptibility ( $chi$ ) quantifies a material's response to an applied magnetic field. For…

Origin — Induced magnetic moment from electron orbital motion (Lenz's Law).

Permanent Dipoles — No permanent atomic magnetic dipoles.

Behavior — Weakly repelled by external magnetic fields.

Movement — From stronger to weaker field regions.

Magnetic Susceptibility ($chi$) — Small and negative (e.g.,

-10^{-5}

-10^{-9}

Relative Permeability ($mu_r$) — Slightly less than 1 (

mu_r < 1

Temperature Dependence — Largely independent of temperature.

Examples — Water, Copper, Bismuth, Gold, Noble gases.

Formula —

\mu_r = 1 + \chi

Don't Interact Really Nice, Temperature Ignored, Susceptibility Negative.

Don't Interact: Diamagnetism is an Induced effect.

Really Nice: Repelled, moves from Near (strong) to far (weak) field.

Temperature Ignored: Temperature Independent.

Susceptibility Negative: Susceptibility is Negative (

chi < 0

(Also remember $mu_r < 1$ and examples like Water, Copper, Bismuth - 'WCB' for 'Weakly Cold Bismuth').