13. FUN WITH MAGNETS
Exericse:
Q1: Fill in the blanks in the following:
(i) Artificial magnets are made in different shapes such as __________, __________ and ____________.
(ii) The Materials which are attracted towards a magnet are called________.
(iii) Paper is not a ______ material.
(iv) In olden days, sailors used to find direction by suspending a piece of ___________.
(v) A magnet always has __________ poles.
Ans:
(i) bar-magnet, horse-shoe magnet, cylinderical magnet
(ii) magnetic material.
(iii) magnetic
(iv) magnet
(v) two
Q2: State whether the following statements are true or false
(i) A cylindrical magnet has only one pole.
(ii) Artificial magnets were discovered in Greece.
(iii) Similar poles of a magnet repel each other.
(iv) Maximum iron filings stick in the middle of a bar magnet when it is brought
near them.
(v) Bar magnets always point towards North-South direction.
(vi) A compass can be used to find East-West direction at any place.
(vii) Rubber is a magnetic material.
Ans:
(i) False
(ii) False
(iii) True
(iv) False
(v) True
(vi) False
(vii) False
Q3: It was observed that a pencil sharpener gets attracted by both the poles of a magnet although its body is made of plastic. Name a material that might have been used to make some part of it.
Ans: A pencil sharpener is made up of plastic and iron, where blade is magnetic material and made up of iron.
Q4: Column I shows different positions in which one pole of a magnet is placed near that of the other. Column II indicates the resulting action between them for each situation. Fill in the blanks.
| Colomn I | Column II |
| N - N | ___________ |
| N - _________ | Attraction |
| S - N | ____________ |
| ________ - S | Repulsion |
Ans:
| Colomn I | Column II |
| N - N | Repulsion |
| N - S | Attraction |
| S - N | Attraction |
| S - S | Repulsion |
Q5: Write any two properties of a magnet.
Ans:
(i) It attracts magnetic materials like irons, nickel and cobalt.
(ii) Oposite poles attract each other while similar poles repel one another.
Q6: Where are poles of a bar magnet located?
Ans: The poles of a bar magnet are located at it's both ends.
Q7: A bar magnet has no markings to indicate its poles. How would you find out near which end is its north pole located?
Ans: When a bar magnet is hanged by its centre point i.e balanced point with a thread. When the bar magnet comes in rest its one of the pole which lives toward the north direction that is the North pole of magnet and remains is South pole. By this activity we can find the north pole of bar magnet very easily.
Q8: You are given an iron strip. How will you make it into a magnet?
Ans: Iron strip is rubbed by one end of magnet for 30 to 40 times after that it makes into a magnet.
Q9: How is a compass used to find directions?
Ans: There are two ends in each magnetic needle are usually pained in a different colour. Its needle indicates the north-south direction when it comes to rest. The compass is then rotated until the north and south marked on the dial are at the two ends of the needle.
Q10: A magnet was brought from different directions towards a toy boat that has been floating in water in a tub. Affect observed in each case is stated in Column I. Possible reasons for the observed affects are mentioned in Column II. Match the statements given in Column I with those in Column II.
| Column I | Column II |
| Boat gets attracted towards the magnet | Boat is fitted with a magnet with north pole towards its head |
| Boat is not affected by the magnet | Boat is fitted with a magnet with south pole towards its head |
| Boat moves towards the magnet if north pole of the magnet is brought near its head | Boat has a small magnet fixed along its length |
| Boat moves away from the magnet when north pole is brought near its head | Boat is made of magnetic material |
| Boat floats without changing its direction | Boat is made up non-magnetic material |
Ans: The Studends do themselves.
