30 Questions
What are the two poles of a magnet?
North Pole, South Pole
According to the Law of Magnetism, how do unlike poles interact with each other?
Attract
What is the polarity of the end pointing towards the Earth's geographical North?
North Pole
In which direction does a magnet come to rest during the Suspension method described?
North-South direction
What happens if there is repulsion between the ends of two magnets brought near each other?
Their poles are like
Which method involves using a known-pole magnet near an unknown-pole magnet to determine the polarity?
Attraction method
What is the only sure way to test for the polarity of a magnet?
Repulsion
What happens when a magnet is freely suspended?
It always come to rest in the North-South direction
In which direction do unlike poles of magnets attract each other?
They attract each other
What is the process of shielding a magnetic material from a magnetic field?
Surrounding the material with a material that diverts the magnetic field lines
What do domains in the domain theory of magnetism consist of?
Tiny magnets called dipoles
According to domain theory, what differentiates magnetic materials from non-magnetic materials?
Arrangement of atoms within the material
What type of materials do magnets attract?
Certain materials like steel
What does the term 'neutral point' refer to in the context of a magnetic field?
A point where magnetic forces are perfectly balanced
What happens to iron fillings when a bar magnet is dipped into them, according to the text?
They cluster around the magnetic poles
What are two properties commonly associated with magnets?
Ability to attract iron and low density
According to the basic law of magnetism, what is a fundamental characteristic of magnetism?
Like poles attract and unlike poles repel
How can you identify the polarities of an unmarked magnet?
By observing its behavior near another known magnet
What happens to the ends of the steel bar when the magnets finish stroking?
They acquire opposite poles to that of the stroking pole.
Why is lifting the permanent magnet high above the steel bar important?
To avoid cancellation of arrangement of dipoles already made.
How are consequent poles of a magnet obtained?
By stroking a steel bar using two like poles of permanent magnets from the centre outwards.
What happens when a magnet has consequent poles?
It never comes to rest if it is suspended.
What is a solenoid?
A cylindrical coil of wires.
How is the polarity of the magnet formed in a steel bar placed inside a solenoid determined?
By the direction of current.
What is the effect of using alternating current on a magnet?
It demagnetizes the magnet by disorganizing the dipoles
How can self-demagnetization be prevented in magnets?
By storing magnets in pairs with unlike poles adjacent to each other
What happens to a magnet when it is hammered several times?
It loses its magnetism
What occurs when a magnet is broken into two or more pieces?
Each piece becomes a complete magnet
Why are magnets stored in pairs with their unlike poles adjacent to each other?
To prevent self-demagnetization due to repulsion
Which method ensures that a magnet doesn't retain some magnetism due to the Earth's magnetic field during demagnetization?
Resting the magnet in East-West direction
Study Notes
Magnetic Poles and Properties
- A magnet has two poles: North Pole (N) and South Pole (S)
- Like poles repel each other, while unlike poles attract each other
- Properties of a magnet include:
- Unlike poles attract, while like poles repel each other
- Attraction power is strongest at the poles
- A freely suspended magnet always comes to rest in the North-South direction
- Magnets attract certain materials, such as steel
Consequent Poles
- Consequent poles of a magnet are double like poles at the centre and ends of a magnetic material
- Consequent poles are obtained when a steel bar is stroked using two like poles of permanent magnets from the centre outwards
- A magnet with consequent poles never comes to rest if it is suspended
Electrical Method of Magnetization
- A solenoid is a cylindrical coil of wires
- A steel bar placed inside a solenoid connected to a direct current supply can be magnetized
- The polarity of the magnet formed depends on the direction of the current
Demagnetization
- Methods of demagnetization include:
- Hammering a magnet while it rests in the East-West direction
- Using an alternating current (AC) supply
- Dropping a magnet
- Demagnetization disorganizes the arrangement of dipoles in the magnet
Storing Magnets
- Magnets tend to become weaker with time due to self-demagnetization
- To prevent self-demagnetization, magnets are stored in pairs with their unlike poles adjacent to each other, with small pieces of soft iron called keepers placed across their ends
Domain Theory of Magnetism
- Magnetic materials are made up of tiny magnets called dipoles divided into regions called domains
- In a magnetized material, dipoles face in the same direction, while in an un-magnetized material, dipoles face in different directions
Test your knowledge on magnet polarity with this quiz. Learn about the properties of magnets and how unlike poles attract while like poles repel each other.
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