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- 1. ELECTROMAGNETS Objectives: 2.4 Demonstrate the effect of a core on the behavior of an electromagnet 2.5 Explain the properties of magnetized matter using the simplified atomic model. 2.6 Factors that affect the magnetic field of an electromagnet 2.7 Determine the mathematical relationship that affects the magnetic force of an electromagnet.
- 2. Factors that affect the Magnetic field of an Electromagnet 1. The core material 1. The current intensity 1. The denser the material the stronger the field Higher the current stronger the magnetic field Number of loops (number of turns) Important More turns gives a stronger field.
- 3. Factors that Affect Magnetic Field Core material Number of loops (turns) Current Intensity
- 4. Cores A Core is the object that is inserted into the solenoid, creating an electromagnet. Different materials influence the strength of the electromagnet. Different metals can be used for the core: iron, steel, nickel or cobalt. Iron is most commonly used because when you turn off the electricity it demagnetizes. Metals like steel remain magnetized thus creating a permanent magnet. Do not want a permanent magnet for the core
- 5. Core Material Ferromagnetic cores strengthen the magnetic field Iron, Steel, nickel & cobalt Iron is a VERY GOOD core Wood, plastic and Aluminum are not very good products for a core
- 6. Number of Loops As the number of loops increases, the strength increases Few loops Many loops
- 7. Current Intensity As the current intensity increases, the strength increases I = 5 amps I = 10 amps
- 8. Which has a stronger magnetic field? A B Iron Wood I = 5 amps I = 5 amps 1 - Number of loops is the same 2 – Intensity is the same 3 – But the core is different Result: (A) Iron is better because it is a ferromagnetic core
- 9. Which has a Stronger Magnetic Field A B Iron Iron I = 2 amps 3 loops I = 2 amps 5 loops # of loops are different Intensity is the same Core is the same Result: B is stronger: more magnetic loops = a stronger magnetic field
- 10. Which has a Stronger Magnetic Field A B Iron Iron I = 2 amps 5 loops I = 10 amps 5 loops # of loops is the same Intensity is different Core is the same Result: B is stronger because current intensity is greater
- 11. Which has a Stronger Magnetic Field A B Nickel Nickel I = 2 amps I = 5 amps 3 loops 5 loops Whenever the loops & the current intensity are different but the cores are the same, use the following equation Strength of field = current intensity x (# of turns) A 15 = 5 amps x 3 turns B 10 = 2 amps x 5 turns A therefore has a stronger magnetic field
- 12. Mathematical Relationship To find the strength of the electromagnet scientists use the following equation: F = IN F is force or strength of the electromagnet I is the current intensity traveling through the wire N is the number of loops around the core Remember
- 13. Which Electromagnet has the Strongest Magnetic Field Current = 10A Turns = 6 60 = 10A x 6 turns Current = 7A Turns = 10 70 = 7A x 10 turns Strongest
- 14. Factors affecting magnetic field: Core material, Number of turns Iron is always the best core material The more loops the stronger the field Current Intensity High current results in stronger intensity
- 15. Origins of Magnetism of Matter Scientists believe that magnetism comes from spinning electrons around the nucleus of the atom. When atoms clump together they form a domain. Enrichment
- 16. Enrichment Origins of Magnetism of Matter Similar electron spins produce a strong domain, where as opposite electron spins cancel one another out and produce a weak domain. If enough domains align in the same direction, this will create a magnetic field.
- 17. Enrichment How to Magnetize an Object Bring the ferromagnetic substance in contact with another magnet. Bang the ferromagnetic substance (example: striking a nail repeatedly). Heat up the substance and cause the domains to align. Run electric current through the ferromagnetic substance. Please note that all of these methods can also de-magnetize a magnet.
- 18. Activities Student Study Guide Module II – 13 # 1 - 5 Module II - 14 Module II –15 Sec. 2.8 Worksheet # 7
- 19. References Student Study Guide Physical Science 416 – MEQ Science Quest, Grenier, Daigle & Rheaune, 1998 Editions Cheneliere Animation Factory Google Images
- 20. Alternative Educational Experiences through e-Learning

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