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1. Magnetism

2. Lesson Objectives Explain the process of magnetization. Differentiate temporary and permanent magnets and their uses at homes and industries. Investigate the factors that affect the strength of electromagnets. Design and construct a simple electric bell based on the concept of electromagnet.

3. What is magnet? Ans : A substance that has property to attract materials like iron, nickel etc. 2. How many types of magnets are there? Ans : There are two types of magnets-Permanent magnet and Temporary magnet. 3. What is permanent magnet? Ans : It is the natural magnet found in a nature. Eg : Lodestone( 4. What is temporary magnet? Ans : It is human-made by magnetization.  

4. 5. What is magnetization? Ans : It is process of making magnetic materials to gain magnetic property using permanent magnet. 6. How many magnetization methods are there? Ans : There are two methods. Method 1 : Stroking-A simple way to let magnetic materials gain magnetic property by stroking several times. Method 2 : Electricity: The magnetic material is wounded by a wire connected to a battery. The materials behaves as magnet as far as battery is connected. Such magnet is called electromagnet.

5. 7. State the uses of temporary and permanent magnets. Ans : Permanent magnets - hard drives, motors, cars, generators, televisions, phones, headphones, speakers, transducers, sensors, etc. Temporary magnets - Iron nails , screws , Metal Bolts.

6. 8. What are the factors that affects the strength of electromagnet? A mount of the current passing through the coil-the greater the current, the greater the strength. N umber of turns in the coils- the greater the number of coils, the greater the strength . Types of iron core-soft iron core gives greater strength.