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PHYSICS, UNIT 06: MAGNETISM, Classwork, Instruction:, Copy the following notes in Physics classwork. Write the notes clearly, neatly, and legibly., I. Answer the following:, 1. Name the different types of magnets., Ans: The two different types of magnets are permanent magnet and temporary, magnet., 2. What are magnetic materials?, Ans: Magnetic materials are those substances which are attracted by magnet., 3. Write one application or use of magnet in the medical field., Ans: Magnetic power creates magnetic fields which can be used in magnetic, therapy., 4. Why magnetic strip is used in credit card?, Ans: The characteristics of magnet is used in credit cards where the magnetic strip, of the card holds the sensitive information of our bank details., 5. What are magnetic field lines?, Ans: The space around the magnet where the magnetic forces work is called, magnetic field lines., 6. Differentiate between magnetic and non-magnetic substances with suitable, examples., Ans:, , Magnetic substances, 1. Magnetic substances are, those which are attracted by, magnets., , Non-magnetic substances, 1. Non-magnetic substances are, those which are not attracted, by magnets., , 2. Example: Iron, Nickel, Cobalt, Example: Wood, Plastic,, Steel etc.,, Rubber, Glass etc.,
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7. Write the different properties of magnets., Ans: The different properties of magnets are:, 1. All the magnets have two poles namely, North seeking pole or North pole and South seeking pole or South pole., 2. The magnetic strength is strongest at the poles of the magnet., 3. The force of attraction of a magnet is greater at its poles than in the middle., 4. Like poles repel each other and unlike poles attract each other., 5. Magnets attract magnetic material such as iron, nickel, cobalt and steel., 8. Explain with diagram the magnetic field around a magnet with magnetic field lines., Ans:, , Magnetic field around a magnet, , The pattern represents the magnetic field of the magnet., The magnetic field lines are the lines which are used to represent the magnetic, fields around the magnets., 9. Write the differences between permanent and temporary magnets., Ans:, Permanent magnet, 1. A permanent magnet is one, which retain its magnetic field, even after the external source is, removed., 2. Steel which belongs to hard, magnetic materials is used in, permanent magnet., 3. It belongs to ferro magnetic, material., 4. It is used in generators and, electric motors., , Temporary magnet, 1. A temporary magnet is one, which retain its magnetic field, only when an external magnetic, field producing it is present., 2. Soft Iron core which belongs, to soft magnetic materials is, used in temporary magnet., 3. It belongs to diamagnetic, material., 4. It is used in cranes and, electric bells., , 10. What are electromagnets?, Ans: A magnet which is formed due to the passage of electric current and which, remains as a magnet as long as the current passes through it is known as an, electromagnet.
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11. Explain the different methods of demagnetising a magnet., Ans: The different methods of demagnetising a magnet are:, 1. Heating the magnet: Heat a magnet for a minute or two and allow it to cool, down. The magnetic ability would be greatly reduced., 2. Hammering: Hammering the magnet in the east-west direction allows the, alignment of magnetic domain and causes the magnet to lose its magnetism., 3. Expose the magnet to alternating current:, Connect the solenoid to an alternating current supply. Place the magnet inside, the solenoid switch on ac supply. Slowly withdraw the magnet in east-west, direction until it is some distance away from the solenoid while ac current still, on.
