1. 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 and cylindrical. (ii) magnetic. (iii) magnetic (iv) magnet. (v) two
2. 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) True vii) False
3. 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. - Iron, nickel or cobalt might have been used to make some part of it like the blade or screw that holds the blade.
5. Write any two properties of a magnet.
Ans. - It attracts material made of Iron, Nickel and Cobalt. Freely suspended magnet points in north - south direction.
6. Where are poles of a bar magnet located?
Ans. - On two ends of the bar magnet.
7. A bar magnet has no markings to indicate its poles. How would you find out near which end is its north pole is located?
Ans. - A bar magnet is hanged in the air with a thread and the end pointing to the geographical north is the north pole of the magnet.
8. You are given an iron strip. How will you make it into a magnet?
Ans. - Take a bar magnet and keep in contact with one of its poles with one edge of the bar of iron. Without lifting the bar magnet, move it along the length of the iron bar till you reach the other end.Lift the magnet and bring the pole (the same pole you started with) to the same point of the iron bar from which we began. Move the magnet again along the iron bar in the same direction as you did before. Repeat this process for about 30-40 times.
9. How is a compass used to find directions?
Ans. - Compass - This is a small glass case containing a magnetized needle pivoted on a nail. The needle can rotate freely.Wherever it is kept, its needle always rests in north-south direction. Normally the north-pole of the needle is painted red or some other indication is given to identify north and south-poles. So using this needle, north and south can be identified.
10. 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 effects are mentioned in Column II. Match the statements given in Column I with those in Column II.
.png)
){kind=link}