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What is Diamagnetism?
Grade Level:
Class 12
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Definition
What is it?
Diamagnetism is a property of materials where they are weakly repelled by an external magnetic field. This happens because the magnetic field causes a tiny, opposing magnetic field within the material itself.
Simple Example
Quick Example
Imagine you have a small toy boat (a diamagnetic material) floating in water. If you try to push it with a very weak magnet, it would slightly move away from the magnet, not towards it. This tiny push away is like diamagnetism.
Worked Example
Step-by-Step
Let's understand how a diamagnetic material reacts to a magnet.
Step 1: Take a piece of pure water (which is diamagnetic) and place it near a strong magnet.
---Step 2: Observe the interaction. You will notice that the water surface slightly dips or moves away from the magnet.
---Step 3: This slight repulsion shows that water is pushing back against the magnet's field.
---Step 4: This push-back is due to the electrons in the water molecules creating a tiny opposing magnetic field when the external magnet is near.
---Step 5: Therefore, water exhibits diamagnetism by being weakly repelled by the external magnetic field.
Answer: Diamagnetic materials like water are weakly repelled by external magnetic fields.
Why It Matters
Understanding diamagnetism is crucial for developing advanced technologies like magnetic levitation for high-speed trains (like those being explored for India's future transport) and in sensitive medical imaging machines (MRI). Scientists and engineers use this knowledge to design materials for various applications, from energy storage to quantum computing.
Common Mistakes
MISTAKE: Thinking diamagnetic materials are attracted to magnets like iron. | CORRECTION: Diamagnetic materials are always weakly REPELLED by magnets, not attracted.
MISTAKE: Believing diamagnetism is a strong effect that is easily seen. | CORRECTION: Diamagnetism is a very WEAK effect, often requiring strong magnets and sensitive instruments to observe clearly.
MISTAKE: Confusing diamagnetism with paramagnetism or ferromagnetism. | CORRECTION: Diamagnetism means repulsion, paramagnetism means weak attraction, and ferromagnetism means strong attraction.
Practice Questions
Try It Yourself
QUESTION: Which of these materials is generally diamagnetic: Wood, Iron, or Nickel? | ANSWER: Wood
QUESTION: If you place a very strong magnet near a small piece of pure water, what kind of interaction would you observe? (Attraction, Repulsion, No interaction) | ANSWER: Repulsion
QUESTION: A material is placed in a strong magnetic field and shows a slight movement away from the field. What magnetic property is this material exhibiting? Explain in one sentence. | ANSWER: Diamagnetism. The material is exhibiting diamagnetism because it is weakly repelled by the external magnetic field.
MCQ
Quick Quiz
Which statement best describes a diamagnetic material?
It is strongly attracted to a magnet.
It is weakly attracted to a magnet.
It is weakly repelled by a magnet.
It shows no interaction with a magnet.
The Correct Answer Is:
C
Diamagnetic materials are characterized by their weak repulsion from an external magnetic field. Options A and B describe ferromagnetic and paramagnetic materials, respectively, while D is incorrect as there is an interaction.
Real World Connection
In the Real World
In India, scientists at institutions like ISRO or DRDO study magnetic properties of materials to develop advanced sensors and shielding for spacecraft and defense equipment. Even in everyday life, the non-stick coating on your tawa or kadhai might involve materials whose magnetic properties are understood through concepts like diamagnetism during their development.
Key Vocabulary
Key Terms
MAGNETIC FIELD: The area around a magnet where its magnetic force can be felt. | REPULSION: The act of pushing something away. | ATTRACTION: The act of pulling something towards. | ELECTRONS: Tiny particles in atoms that carry electric charge and create small magnetic moments. | EXTERNAL: Coming from outside.
What's Next
What to Learn Next
Now that you understand diamagnetism, you should explore paramagnetism and ferromagnetism next! Learning about these will help you compare and contrast different magnetic behaviors and see how materials react differently to magnets, which is super useful for many technologies.
