Magnets attract magnetic substances such as iron, nickel, cobalt etc. They can also repel :

1. Fundamentals of Magnetism: Poles and Fields (basic)

At its heart, magnetism is a force that acts even without physical contact. You might have seen this yourself when holding two magnets close: they either snap together or push apart with a mysterious, invisible pressure. This happens because every magnet has two distinct regions called poles—the North (N) and the South (S). A fundamental rule of nature is that like poles repel each other, while opposite poles attract. This is so powerful that you can even make a magnet "float" in mid-air by placing it above another magnet with the same poles facing each other Science, Class VIII, Exploring Forces, p.69.

To visualize how this force works, we use the concept of magnetic field lines. Think of these as an invisible map showing the direction and strength of the magnetic force. These lines are unique: they are continuous closed loops. Outside the magnet, they emerge from the North pole and enter the South pole. However, inside the magnet, the direction is reversed, traveling from South to North Science, Class X, Magnetic Effects of Electric Current, p.197. A crucial rule to remember is that field lines never intersect; if they did, a compass placed at that point would have to point in two directions at once, which is physically impossible.

While we often think magnets only "attract" things like iron, the reality is more nuanced. Materials respond to magnetic fields in three main ways:

• Ferromagnetic: Strongly attracted (e.g., Iron, Nickel, Cobalt).
• Paramagnetic: Very weakly attracted.
• Diamagnetic: These actually repel magnetic fields. Materials like copper, water, and bismuth develop a weak internal field opposite to the magnet, causing a slight push away.

Property	Description
Field Strength	Determined by how crowded the field lines are; strongest at the poles.
Solenoid Behavior	A coil of wire (solenoid) creates a magnetic field identical to a bar magnet when electricity flows through it Science, Class X, Magnetic Effects of Electric Current, p.201.

Sources: Science, Class VIII, Exploring Forces, p.69; Science, Class X, Magnetic Effects of Electric Current, p.197; Science, Class X, Magnetic Effects of Electric Current, p.201

2. Magnetic Field Intensity and Permeability (intermediate)

To understand how magnets interact with the world, we must first distinguish between the "effort" we put into creating a magnetic field and the "result" we get inside a material. Imagine you are trying to push water through two different sponges—one very porous and one very dense. The pressure you apply is the same, but the amount of water that actually flows through depends on the sponge's nature. In magnetism, this "pressure" is known as Magnetic Field Intensity (H), and the material's "porosity" is its Magnetic Permeability (μ).

Magnetic Field Intensity (H), often called the magnetizing force, represents the external influence used to create a magnetic field. For example, when an electric current flows through a long straight solenoid, it generates a magnetic field that is uniform at all points inside Science, Class X, Magnetic Effects of Electric Current, p.202. This intensity (H) depends solely on the current and the geometry of the wire, not on the material placed inside it. It is the "pushing force" of magnetism.

However, the actual magnetism that develops inside a substance—the Magnetic Flux Density (B)—depends on the material's Permeability (μ). Permeability is a measure of how much "permission" a material gives to magnetic lines of force to pass through it. We express this relationship with a fundamental formula: B = μH. As we learned in earlier grades, magnets exert force on magnetic materials without being in contact with them Science, Class VIII, Exploring Forces, p.69; permeability is the physical property that dictates the strength of that force.

Materials react differently to this force based on their permeability:

• Ferromagnetic materials (like iron, nickel, and cobalt) have very high permeability, meaning they amplify the magnetic field significantly and are strongly attracted Science, Class VIII, Electricity: Magnetic and Heating Effects, p.47.
• Paramagnetic materials have a permeability slightly greater than a vacuum and are weakly attracted.
• Diamagnetic materials (like water, bismuth, or copper) actually have a permeability less than that of a vacuum. Because they "resist" the field, they develop an internal magnetic field in the opposite direction, leading to a weak repulsion rather than attraction.

Sources: Science, Class X, Magnetic Effects of Electric Current, p.202; Science, Class VIII, Exploring Forces, p.69; Science, Class VIII, Electricity: Magnetic and Heating Effects, p.47

3. Electromagnetism and Modern Applications (intermediate)

For centuries, electricity and magnetism were studied as two entirely separate forces. This changed in 1820 when Hans Christian Oersted noticed a compass needle deflect when placed near a wire carrying an electric current. This accidental observation proved that moving charges (electricity) generate a magnetic field in their surroundings Science, Class X (NCERT 2025 ed.), Magnetic Effects of Electric Current, p.195. This discovery laid the foundation for modern technologies like radio and fiber optics.

One of the most practical applications of this principle is the solenoid — a long coil containing many circular turns of insulated copper wire wrapped in a cylindrical shape. When current passes through it, the solenoid behaves exactly like a bar magnet, with one end acting as a North pole and the other as a South pole Science, Class X (NCERT 2025 ed.), Magnetic Effects of Electric Current, p.201. A unique feature of the solenoid is the field inside the coil: the magnetic field lines are parallel straight lines, meaning the magnetic field is uniform (identical in strength and direction) at all points inside the solenoid Science, Class X (NCERT 2025 ed.), Magnetic Effects of Electric Current, p.202.

While we often associate magnets with attracting iron (ferromagnetism), materials actually respond to magnetic fields in different ways. While ferromagnetic materials like iron and nickel are strongly attracted, diamagnetic substances — such as water, copper, and bismuth — actually exhibit a weak repulsion. When these materials are placed in an external magnetic field, they develop an induced field in the opposite direction, resulting in this subtle repulsive force. This reminds us that magnetism is a universal property of all matter, though its effects vary significantly across different substances.

Material Type	Reaction to Magnetic Field	Examples
Ferromagnetic	Strong Attraction	Iron, Cobalt, Nickel
Diamagnetic	Weak Repulsion	Water, Copper, Bismuth

Sources: Science, Class X (NCERT 2025 ed.), Magnetic Effects of Electric Current, p.195; Science, Class X (NCERT 2025 ed.), Magnetic Effects of Electric Current, p.201; Science, Class X (NCERT 2025 ed.), Magnetic Effects of Electric Current, p.202

4. Earth's Magnetism (Geomagnetism) (intermediate)

Think of the Earth not just as a rotating sphere of rock, but as a colossal spherical magnet. This magnetic field is generated deep within the planet by the geodynamo—the movement of molten iron and nickel in the outer core. Because this liquid metal is conductive and in constant motion, it creates electric currents that generate our planet's protective magnetic envelope. Interestingly, the Earth's magnetic field is approximately a magnetic dipole, meaning it behaves like a giant bar magnet tilted at an angle to the Earth's rotational axis Physical Geography by PMF IAS, Earths Magnetic Field (Geomagnetic Field), p.74. However, unlike a static bar magnet, this field is dynamic and shifts over time.

When you use a compass, it is crucial to understand that it points toward Magnetic North, not Geographic North (True North). The angle between these two directions is known as Magnetic Declination. Navigators must account for this angle to avoid going off-course Physical Geography by PMF IAS, Earths Magnetic Field (Geomagnetic Field), p.76. Additionally, the magnetic field lines aren't always parallel to the ground; they curve into the Earth. The angle these lines make with the horizontal surface is called Magnetic Inclination or Dip. At the Magnetic Dip Poles, a magnetic needle would point vertically straight down or up (90° dip) Physical Geography by PMF IAS, Earths Magnetic Field (Geomagnetic Field), p.72.

Feature	Geographic Pole	Magnetic Pole
Definition	Fixed points where the axis of rotation meets the surface.	Points where magnetic field lines are perfectly vertical (Dip Poles).
Stability	Remains constant.	Constantly drifting and can even reverse over millennia.

A fascinating nuance in physics is that what we call the "North Magnetic Pole" is technically the South Pole of the Earth's internal magnetic field. This is because the north-seeking end of a compass magnet is attracted to it (opposites attract!). Furthermore, the Earth's magnetic field is not perfectly symmetrical; therefore, the North and South magnetic poles are not antipodal—meaning they are not exactly on opposite sides of the planet from one another Physical Geography by PMF IAS, Earths Magnetic Field (Geomagnetic Field), p.72.

Sources: Physical Geography by PMF IAS, Earths Magnetic Field (Geomagnetic Field), p.72; Physical Geography by PMF IAS, Earths Magnetic Field (Geomagnetic Field), p.74; Physical Geography by PMF IAS, Earths Magnetic Field (Geomagnetic Field), p.76

5. Ferromagnetism and Paramagnetism: The Attractors (exam-level)

To understand why some materials are 'magnetic' and others aren't, we must look at the atomic level. Every atom contains electrons that spin and orbit the nucleus, acting like tiny loop currents that create miniature magnetic fields. In most substances, these tiny magnets point in random directions and cancel each other out. However, in Ferromagnetic materials — like iron, nickel, and cobalt — these atomic magnets naturally align into clusters called domains. When you bring a magnet near them, these domains snap into alignment with the external field, creating a powerful attraction. This is why iron is the preferred material for the core of an electromagnet; it 'multiplies' the magnetic strength significantly Science, Class VIII NCERT (Revised ed 2025), Electricity: Magnetic and Heating Effects, p.50. Interestingly, the magnetic properties of iron can be further enhanced or altered by creating alloys; for instance, adding manganese can improve the magnetic qualities of iron used in high-speed tools Certificate Physical and Human Geography, GC Leong (Oxford University press 3rd ed.), Manufacturing Industry and The Iron and Steel Industry, p.284.

While Ferromagnetism is the 'strong' version of attraction, Paramagnetism is its subtler cousin. Paramagnetic materials (like aluminum or oxygen) have a small, positive magnetic susceptibility, meaning they are weakly attracted to a magnetic field. Unlike ferromagnetic materials, they do not have permanent 'domains' and lose their magnetism the moment the external field is removed. On the opposite end of the spectrum lies Diamagnetism. Instead of being attracted, diamagnetic substances like copper, bismuth, water, and graphite develop a weak induced magnetic field in the opposite direction to the applied force, resulting in a gentle repulsion. Although diamagnetism is a fundamental property found in all matter, it is usually so weak that it is masked by the stronger forces of ferromagnetism or paramagnetism.

Type	Response to Magnets	Retains Magnetism?	Examples
Ferromagnetic	Strongly Attracted	Yes (can become permanent)	Iron (Fe), Nickel (Ni), Cobalt (Co)
Paramagnetic	Weakly Attracted	No	Aluminum, Oxygen, Platinum
Diamagnetic	Weakly Repelled	No	Copper (Cu), Bismuth, Water (H₂O)

Sources: Science, Class VIII NCERT (Revised ed 2025), Electricity: Magnetic and Heating Effects, p.50; Certificate Physical and Human Geography, GC Leong (Oxford University press 3rd ed.), Manufacturing Industry and The Iron and Steel Industry, p.284

6. Diamagnetism: The Science of Repulsion (exam-level)

While we often think of magnets as 'sticky' tools that attract metals like iron, there is a fascinating category of materials that do the exact opposite. This is diamagnetism. In these substances—such as bismuth, copper, water, and graphite—the atoms respond to an external magnetic field by creating their own internal magnetic field in the opposite direction. This results in a weak, yet fundamental, repulsive force. Think of it as a push-back mechanism; when a magnet approaches, the diamagnetic material tries to move away from the stronger part of the field.

At its root, this behavior is a manifestation of Lenz’s Law at the atomic level. We know that moving electric charges exert forces and create magnetic fields Science, Class X (NCERT 2025 ed.), Magnetic Effects of Electric Current, p.206. In diamagnetic materials, the orbital motion of electrons is subtly altered by the external field to produce a counter-magnetism. Because this induced field opposes the external one, these materials are said to have negative magnetic susceptibility. This is distinct from the 'floating' effect seen when like poles of two magnets face each other Science, Class VIII (NCERT Revised ed 2025), Exploring Forces, p.69, as diamagnetism is a property of the material itself rather than a permanent pole interaction.

Interestingly, diamagnetism is a universal property present in all matter. However, it is an extremely weak force. In materials like iron or nickel (ferromagnetic), this repulsion is completely masked by powerful attractive forces. It is only in substances where these stronger magnetic effects are absent that we can observe the pure, quiet repulsion of diamagnetism.

Magnetic Property	Direction of Induced Field	Reaction to Magnet
Diamagnetism	Opposite to external field	Weak Repulsion
Paramagnetism	Same as external field	Weak Attraction
Ferromagnetism	Same as external field	Strong Attraction

Sources: Science, Class X (NCERT 2025 ed.), Magnetic Effects of Electric Current, p.206; Science, Class VIII (NCERT Revised ed 2025), Exploring Forces, p.69; Science, Class VIII (NCERT Revised ed 2025), Electricity: Magnetic and Heating Effects, p.47

7. Solving the Original PYQ (exam-level)

Now that you have mastered the fundamental classification of matter based on magnetic properties, this question serves as the perfect application of those building blocks. You've learned that substances react differently to an external magnetic field based on their atomic structure and magnetic susceptibility. While your intuition, shaped by daily life, suggests magnets only attract, this question tests your deeper understanding of the sign of the magnetic response. In diamagnetic substances, the induced magnetic field is always opposite to the applied external field, leading to a weak but definitive repulsive force. This is why (C) diamagnetic substances is the correct answer.

To arrive at this conclusion, think like a physicist: attraction occurs when the material's internal field aligns with the external magnet, but repulsion occurs when it opposes it. Diamagnetism is a universal property where substances like water, copper, and bismuth exhibit this negative response. As noted in ScienceDirect, while this effect is often weak and masked by other types of magnetism, it is the only category among the options where the inherent reaction is repulsion rather than attraction.

UPSC often uses common misconceptions as traps. Options (A) paramagnetic and (B) ferromagnetic are the most common pitfalls; students often confuse them because both involve attraction (weak and strong, respectively). Option (D) non-magnetic is a layman's distractor; in the realm of competitive science, we recognize that almost all matter interacts with magnetic fields in some way. By focusing on the direction of the induced field, you can easily bypass these traps and identify that only diamagnets push back against the magnetic source, as detailed in University of Strathclyde Engineering Research.