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प्रश्न
Answer the following in detail.
List four methods of magnetizing a magnetic substance.
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उत्तर
Methods of magnetizing a magnetic material are :
- Single-touch method – A magnet is rubbed along the magnetic substance from one end to another.
- Double-touch method – Opposite poles of two magnets are placed next to each other at the centre of the magnetic substance and rubbed in opposite direction along it.
- Magnetizing by induction – It is a method to make temporary magnets under the influence of a magnetizing force. The magnetic properties disappear when the influence of the magnetizing force is removed.
(A permanent magnet is brought close to the magnetic substance but not touched.) - Electric current – A magnet made by using electric current is called an electromagnet. It is a temporary magnet and stops behaving like a magnet when the current is stopped. Electromagnets can become permanent magnets if certain materials like steel and special alloys are placed in a coil and a very strong current is passed through the coil.
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संबंधित प्रश्न
What is a magnet?
How are the magnets kept safely? What is the role of keepers in storing the magnets?
Fill in the blank.
Magnetic poles always exist in ...............
Bar magnets are often stored in pairs as shown in the figure. E and F being pieces of metal.
Why are E and F placed in contact with the poles of the magnets as shown in the diagram?
The figure shows a freely suspended magnet in the rest position. Copy the diagram and on its show:
- Angle of declination
- Angle in dip
What do you understand by the term magnetic declination?
Give scientific reason:
Two steel needles hanging from the lower end of a vertical bar magnet do not hang vertically.
Write a short note on lighting conductors.
State the laws of magnetism.
People who made mariner’s compass for the first time.
