\n5. Boat floats without changing its direction<\/td>\n | (e) Boat is made up non-magnetic material<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n Answer: \n1. (d), \n2. (e), \n3. (b), \n4. (a), \n5. (c).<\/p>\n NCERT Extended Learning Activities and Projects<\/span><\/p>\nQuestion 1. \nUsing a compass, find the direction in which windows and entrance to your house or classroom open. \nHint: \nDo it yourself.<\/p>\n Question 2. \nTry to place two equal sized bar magnets one above the other such that their north poles are on the same side. Note what happens and write your observations in your notebook. \nHint: \nDo it yourself.<\/p>\n Question 3. \nFew iron nails and screws got mixed with the wooden shavings while a carpenter was working with them. How can you help him in getting the nails and screws back from the scrap without wasting his time in searching with his hands? \nHint: \nWe can suspend and rotate a magnet inside the mixture. All the iron nails and screws will get stick to it and separate from the mixture.<\/p>\n <\/p>\n Question 4. \nYou can make an intelligent doll, which picks up the things it likes (Fig. 13.17 on NCERT). Take a doll and attach a small magnet in one of its hands. Cover this hand with small gloves so that the magnet is not visible. Now, your intelligent doll is ready. Ask your friends to bring different objects near the doll\u2019s hand. Knowing the material of the object you can tell in advance whether the doll would catch it or not. \nHint: \nDo it yourself.<\/p>\n Activity 1<\/span><\/p>\nAim: To identify the materials which are attracted by magnet and not attracted by the magnet. \nMaterials Required: A small bar magnet and waste materials from your house or school. \nProcedure:<\/p>\n \n- Fix a small bar magnet to a wooden stick.<\/li>\n
- Move this magnet stick over the dry wastes from different places such as office, home, etc., and record your observations.<\/li>\n<\/ul>\n
Observations:<\/p>\n \n\n\n\n Waste materials<\/p>\n<\/td>\n | Materials that get attracted to the magnet<\/td>\n | \n Materials that do not get attracted to magnet<\/p>\n<\/td>\n<\/tr>\n | \n1. Wastes from school<\/td>\n | Pins, blades<\/td>\n | Paper, pencil, eraser<\/td>\n<\/tr>\n | \n2. Wastes from home<\/td>\n | Iron scrap, blade<\/td>\n | Broken plastic items, empty toothpaste tube, paper scrap, plastic bag<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n Conclusion<\/p>\n \n- Iron, steel, cobalt, nickel and their alloys are magnetic substances which are attracted by a magnet.<\/li>\n
- Aluminium, copper, brass, stainless steel, wood, leather and plastic are non-magnetic substances which are not attracted by a magnet.<\/li>\n<\/ul>\n
Poles of a Magnet: A magnet has two poles, viz, North Pole and South Pole. The magnetic power is concentrated on the poles of a magnet. When a bar magnet is suspended to move freely, it always points in the north-south direction. The north pole of the magnet points towards the geographical north and the south pole of the magnet points towards the geographical south.<\/p>\n Activity 2<\/span><\/p>\nAim: To show that a magnet always comes to rest in a fixed direction. \nMaterials Required: Bar magnet and wooden stand. \nProcedure:<\/p>\n \n- Mark one end of a magnet for identification.<\/li>\n
- Hang it from a wooden stand with the help of a thread.<\/li>\n
- Allow it to come to rest.<\/li>\n
- Mark the direction in which the magnet comes to rest on the ground.<\/li>\n
- Now rotate the magnet and observe the direction in which it comes to rest again.<\/li>\n<\/ul>\n
\nObservations: The magnet always comes to rest in the same direction. The direction is found to be north-south direction. \nConclusion: A freely suspended bar magnet always comes to rest in a particular direction, which is the North-South direction.<\/p>\n
Interaction between poles of Magnet \n \ni. Like poles repel each other: This means when north pole of a magnet is brought near the north pole of another magnet, both repel each other. The same holds true for the south poles of two magnets. \nii. Unlike poles attract each other: This means when north pole of a magnet is brought near the south pole of another magnet, both attract each other.<\/p>\n Lodestone: The magnetic stone indicating directions used by sailors in olden days to identify directions is called lodestone. \nStrength of a magnet \ni. The strength of a magnet is maximum at its poles. \nii. The strength of magnet decreases as we go towards the mid-point of a magnet. \niii. The strength of a magnet is very less or zero at the mid-point of a magnet. It is called neutral point.<\/p>\n <\/p>\n Activity 3<\/span><\/p>\nAim: To show that magnetic force is maximum at the ends of a magnet. \nMaterials Required: Bar magnets and iron filings. \nProcedure:<\/p>\n | |