13-Fun with Magnets - PPT.pptx

By divyanshu

1. PREPARED BY :- Mr. AVNEESH SAXENA T.G.T.(SCIENCE) CLASS-VI K.V. NO.02, AFS, CHAKERI, KANPUR Saturday, December 18, 2021 Mr. AVNEESH SAXENA 1

2. CHAPTER - 13 FUN WITH MAGNETS Saturday, December 18, 2021 Mr. AVNEESH SAXENA 2

3. -:Discovery of Magnets :- Saturday, December 18, 2021 Mr. AVNEESH SAXENA 3 He used to take his herd of sheep and goats to the nearby mountains for grazing. He would take a stick with him to control his herd. The stick had a small piece of iron attached at one end . One day he was surprised to find that he had to pull hard to free his stick from a rock on the mountainside. It seemed as if the stick was being attracted by the rock. The rock was a natural magnet and it attracted the iron tip of the shepherd's stick. It is said that this is how natural magnets was discovered. Roughly 4,000 years ago, a Greek shepherd named Magnes is said to have been tending his sheep in a region of northern Greece called Magnesia. A Natural Magnets On A Hillside!

4. -: Magnet :- Magnet is a material which attracts materials like iron, cobalt, nickel etc. There are two main types of magnets. They are natural magnets and artificial magnets . Saturday, December 18, 2021 Mr. AVNEESH SAXENA 4

5. -: Magnetic and Non Magnetic Materials :- Magnetic Materials are materials which are attracted by magnets . Eg :- Iron, Cobalt, Nickel, Steel etc. Non Magnetic Materials are materials which are not attracted by magnets . Eg :- Wood, Plastic, Rubber, Glass etc. Saturday, December 18, 2021 Mr. AVNEESH SAXENA 5

6. -: Shapes of Magnets :- Magnets are of different shapes. They are bar magnet, horse shoe magnet, cylindrical magnet etc. Saturday, December 18, 2021 Mr. AVNEESH SAXENA 6

7. -: Shapes of Magnets :- Saturday, December 18, 2021 Mr. AVNEESH SAXENA 7

8. -: Poles of a Magnet :- The two ends of a magnet where the attraction is maximum are called the poles of the magnet . A magnet has two poles called north pole and south pole . A freely suspended bar magnet points in the North – South direction . The end of the magnet which points towards the north is called the North pole. The end of the magnet which points towards the south is called the South pole. Saturday, December 18, 2021 Mr. AVNEESH SAXENA 8

9. Saturday, December 18, 2021 Mr. AVNEESH SAXENA 9 The Magnetic Poles always exist in pairs . When an attempt is made to separate the magnetic poles by breaking a magnet , the it is observed that the two parts become a complete magnet. New magnetic poles are developed at broken ends. -: Poles of a Magnet :-

10. -: How to Make a Magnet :- Activity :- Take a rectangular piece of iron , a needle, a blade or an iron nail. Keep it on a table. Take a bar magnet and keep one of its pole on one end of the piece of iron . Move it along the piece of iron till the other end. Then lift the magnet and repeat this process 30 to 40 times . Then the piece of iron becomes a magnet . N Saturday, December 18, 2021 Mr. AVNEESH SAXENA 10

11. -: Magnetic Compass :- A magnetic compass is a device used to find directions. It has a metal case with a glass cover . A magnetic needle which can rotate freely is pivoted inside the case. It also has a dial marked with directions inside it. Metal case Glass cover Magnetic needle Dial Saturday, December 18, 2021 Mr. AVNEESH SAXENA 11

12. -: How to make a Magnetic Compass :- Activity :- Magnetise an iron needle with a bar magnet. Insert the needle through a piece of thermocole . Float it in a cup of water. The needle points in the North – South direction. Saturday, December 18, 2021 Mr. AVNEESH SAXENA 12

13. -: Attraction and Repulsion Between Magnets :- The opposite poles of two magnets attract each other. The similar poles of two magnets repel each other. Saturday, December 18, 2021 Mr. AVNEESH SAXENA 13

14. -: Properties of Magnets :- i) Magnets attract materials like iron, cobalt, nickel etc . ii ) A freely suspended magnet points in the north – south direction . Saturday, December 18, 2021 Mr. AVNEESH SAXENA 14

15. -: Properties of Magnets :- iii ) The opposite poles of two magnets attract each other and the similar poles of two magnets repel each other. Saturday, December 18, 2021 Mr. AVNEESH SAXENA 15 Similar Poles Opposite Poles

16. -: A Few Cautions About Magnets :- Saturday, December 18, 2021 Mr. AVNEESH SAXENA 16 Precautions to protect magnets from losing their magnetic properties Never drop magnets from heights. Never heat a magnet. Do not hammer a magnet .

17. -: A Few Cautions About Magnets :- Magnets should be kept away from radio, television, music systems, computers , mobile phones, cassettes, compact discs etc . Saturday, December 18, 2021 Mr. AVNEESH SAXENA 17

18. -: A Few Cautions About Magnets :- Store your magnets safely. Saturday, December 18, 2021 Mr. AVNEESH SAXENA 18

19. Saturday, December 18, 2021 Mr. AVNEESH SAXENA 19 It is used in a Compass to find directions It is used in factories for lifting heavy masses of iron . It is used in construction of telephones, electric bells etc . -: Uses Of Magnets:-

20. Saturday, December 18, 2021 Mr. AVNEESH SAXENA 20 It is used to separate iron & steel from non-magnetic materials . Use a Magnet for Pacemakers, Magnetic Resonance Imaging (MRI) etc . -: Uses Of Magnets:-

21. Saturday, December 18, 2021 Mr. AVNEESH SAXENA 21 Laptop -: Application of Magnets :-

22. Saturday, December 18, 2021 Mr. AVNEESH SAXENA 22

23. Saturday, December 18, 2021 Mr. AVNEESH SAXENA 23 Artificial Magnet was discovered in Greece. A)True B) False Answer Verified Hint: To solve this question, we should know where the magnets were discovered first and what type of magnets were discovered there. If Greece is the first place where artificial magnets were discovered then the statement is true. But if Greece is not the place where artificial magnets were discovered, then the statement is wrong . Complete step by step answer: Artificial magnets were discovered by William Gilbert in the sixteen hundreds in England . The first natural magnet was discovered by the Greeks. So, the correct option is (B) i. e, False.

24. Saturday, December 18, 2021 Mr. AVNEESH SAXENA 24