Fun with Magnets

1. (i) Artificial magnets are made in different shapes such as _bar magnets_,__horse-shoe magnets_, and __cylindrical magnets_.(ii) Materials which are attracted towards magnets are called magnetic materials.
   (iii) Paper is not a __magnetic_material.
   Paper is not attracted by magnet. Hence, it is not a magnetic material.
   (iv) In olden days, sailors used to find direction by suspending a piece of bar magnet .
   A freely suspended magnet always comes to rest in the North-South direction. Hence, sailors used to find direction by suspending a piece of bar magnet.
   (v) A magnet always has __two__poles.
   A magnet has two poles called the south pole (S) and the north pole (N).
   
2. (i) False
   Magnets always have two poles; the north pole and the south pole. A cylindrical magnet also has two poles.
   (ii) False
   Artificial magnets were not discovered in Greece. Only natural magnets were discovered in Greece.
   (iii) True
   Like poles of magnets repel each other, while unlike poles of magnets attract each other. The south pole of a magnet attracts the north pole of another magnet and repels the south pole of that magnet.
   (iv) False
   The amount of iron filings that stick to a bar magnet depends on the strength of the magnet. The magnetism of a bar magnet is maximum at its two poles and minimum in the middle. Hence, maximum iron filings will stick at the two ends of the magnet and minimum in the middle.
   (v) True
   A freely suspended magnet always points towards the North−South direction.
   (vi) True
   A magnetic compass always points towards the North−South direction.
   
   Ifthe North−South direction is known, then the East−West direction can also be determined. This direction is perpendicular to the North-South direction, i.e., perpendicular to the compass needle in the same plane.
   (vii) False
   Rubber is not attracted by a magnet. Hence, it is a non-magnetic material.
3. Theblade of a pencil sharpener is made of iron. Iron is a magnetic material. Since magnets can attract objects made of magnetic materials, a pencil sharpener gets attracted towards both poles of a magnet.
   
4. Likemagnetic poles repel each other, while unlike magnetic poles attract each other.
   

   Column I	Column II
   N − N	Repulsion
   N − S	Attraction
   S − N	Attraction
   S− S	Repulsion

5. Two properties of a magnet are:
   (i) Magnets attract objects made of magnetic materials like iron.
   (ii) Like magnetic poles repel each other, while unlike magnetic poles attract each other.
   
6. At both ends.
   The north pole (N) and the south pole (S) of a bar magnet are located at its two ends (as shown in the given figure).
   
   
7. Afreely suspended bar magnet always comes to rest in the North−South direction. The north facing end of the magnet is its north pole, and the south facing end is its south pole (as shown in the given figure).
   
   Hence, the unknown poles of a bar magnet can be marked by suspending it freely by a string.
   
8. ‘Touch and stroke’ method can be used to make an iron strip into a magnet. For this, a bar magnet is required. The bar magnet is moved along the length of the iron strip starting from one end to the other end (as shown in the given figure).
   
   Then, the bar magnet is lifted from the other end and brought to the starting point again with the same pole of the bar magnet. On repeating the process for at least 40 to 50 times, the iron strip will become a bar magnet with two poles.
   
9. A compass always points towards the North−South direction. The red arrow of the compass needle indicates its north pole. The arrow always points in the North direction (as shown in the given figure).
   
   If we know the North direction, then we can find all the other three directions at that place. If North is towards the front, then South would be towards the back, East towards the right of North, and West towards the left of North.
   

10. S. No	Column I	Column II
    1.	Boat gets attracted towards the magnet	Boat is made of a magnetic material
    2.	Boat is not affected by the magnet	Boat is made of a non-magnetic material
    3.	Boat moves towards the magnet when the north pole of the magnet is brought near its head	Boat is fitted with a magnet with the south pole towards its head
    4.	Boat moves away from the magnet when the north pole is brought near its head	Boat is fitted with a magnet with the north pole towards its head
    5.	Boat floats without changing its direction	Boat has a small magnet fixed along its length

    1. Magnetic materials get attracted towards a magnet.
    2. Non-magnetic materials do not get attracted towards a magnet.
    3. Unlike poles of magnets attract each other.
    4. Like poles of magnets repel each other.
    5. Magnets always point towards the North-South direction.