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Física y química 3º E.S.O.

Física y química 3º E.S.O.

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Física y química 3º E.S.O.

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  1. Física y química 3º E.S.O. THIRD TERM Unit 5: Electricity and magnetism U_5_6_Magnetic fields and magnets U.5_6 d1

  2. Bloque 4. El movimiento y las fuerzas. 4.1. Las fuerzas. Efectos de las fuerzas. 4.2. Fuerzas de especial interés: peso, normal, rozamiento, fuerza elástica. 4.3. Principales fuerzas de la naturaleza: gravitatoria, eléctrica y magnética. Criterios de evaluación C.E.4.8. Conocerlos tipos de cargas eléctricas, su papel en la constitución de la materia y las características de las fuerzasque se manifiestan entre ellas. . Estándares de aprendizaje evaluables E.A.4.8.1. Explica la relación existente entre las cargas eléctricas y la constitución de la materia y asocia la carga eléctrica de los cuerpos con un exceso o defecto de electrones. E.A.4.8.2. Relaciona cualitativamente la fuerza eléctrica que existe entre dos cuerpos con su carga y la distancia que los separa, y establece analogías y diferencias entre las fuerzas gravitatoria y eléctrica. Criterios de evaluación C.E.4.9. Interpretar fenómenos eléctricos mediante el modelode cargaeléctricay valorar la importanciade la electricidaden la vida cotidiana. Estándares de aprendizaje evaluables E.A.4.9.1. Justifica razonadamente situaciones cotidianas en las que se pongan de manifiesto fenómenos relacionados con la electricidad estática. Criterios de evaluación C.E.4.10. Justificar cualitativamentefenómenos magnéticos y valorarla contribución del magnetismo en el desarrollo tecnológico. Estándares de aprendizaje evaluables E.A.4.10.1. Reconoce fenómenos magnéticos identificando el imán como fuente natural del magnetismo y describe su acción sobre distintos tipos de sustancias magnéticas. E.A.4.10.2. Construye, y describe el procedimiento seguido pare ello, una brújula elemental para localizar el norte utilizando el campo magnético terrestre. Criterios de evaluación C.E.4.11. Comparar los distintostiposde imanes, analizar su comportamiento y deducir medianteexperienciaslas característicasde lasfuerzas magnéticas puestas de manifiesto, asícomosurelación conla corriente eléctrica. Estándares de aprendizaje evaluables E.A.4.11.1. Comprueba y establece la relación entre el paso de corriente eléctrica y el magnetismo, construyendo un electroimán. E.A.4.11.2. Reproduce los experimentos de Oersted y de Faraday, en el laboratorio o mediante simuladores virtuales, deduciendo que la electricidad y el magnetismo son dos manifestaciones de un mismo fenómeno. U.5_6 d2

  3. 5.5.2. The cause of magnetism Nowadays we know that electric currents cause magnetism. For example, Oersted discovered in 1819 that a compass needle moves when is closed to an electrical current. A current flowing through a circular wire is analogous to an electron that orbits a proton in an atom. We know that a current-carrying wire produces a perturbation in the space called magnetic field U.5_6 d3

  4. 5.5.2. The cause of magnetism Magnetism and electricity are very closely related. Each atom that makes up a substance has electrons that spin as they rotate about the nucleus. In some elements (iron, cobalt, nickel) this motion creates a net perturbation, a magnetic effect, around the atom that we call magnetic field U.5_6 d4

  5. 5.6.1. Magnetic forces act at a distance Since magnetic forces act at a distance, we use a magnetic field to represent a region in which each point is affected by a magnetic force. U.5_6 d5

  6. 5.6.1. Magnetic forces act at a distance In order to have an overall representation of the magnetic field, we draw lines of magnetic field Map of magnetic field lines of the Sun U.5_6 d6 https://www.universetoday.com/71872/amazing-image-map-of-magnetic-field-lines-of-the-sun/

  7. 5.6.1. Magnetic forces act at a distance When we want to represent the magnetic field at one particular point, we use the magnetic field vector U.5_6 d7

  8. 5.6.1. Magnetic forces act at a distance The representation of magnetic field lines is very useful in visualizing the strength and direction of the magnetic field. The direction of the magnetic field is the direction that the north pole of a compass needle points U.5_6 d8

  9. 5.6.1. Magnetic forces act at a distance The representation of magnetic field lines is very useful in visualizing the strength and direction of the magnetic field. The direction of the magnetic field is the direction that the north pole of a compass needle points U.5_6 d9

  10. 5.6.1. Magnetic forces act at a distance The direction of the magnetic field is the direction that the north pole of a compass needle points Notice that the magnetic field vector points from north to south and so do the magnetic field lines U.5_6 d10

  11. 5.6.1. Magnetic forces act at a distance A magnet on a pivot is free to rotate. It is placed in an uniform magnetic field pointing to the right as shown. Which way will it turn? U.5_6 d11

  12. 5.6.1. Magnetic forces act at a distance Draw the magnetic field lines: U.5_6 d12

  13. 5.6.1. Magnetic forces act at a distance Two forces are acting on the needle at time. This is called a torque U.5_6 d13

  14. 5.6.1. Magnetic forces act at a distance The direction of the magnetic field is the direction that the north pole of a compass needle points Notice that the magnetic field vector points from north to south and so do the magnetic field lines U.5_6 d14

  15. 5.6.1. Magnetic forces act at a distance The representation of magnetic field lines is very useful in visualizing the strength and direction of the magnetic field. The strength of the magnetic field is propotional to the torque felt by the compass needle Torque U.5_6 d15

  16. 5.6.2. Magnetic fields produced by magnets a) Magnetic field vectors and magnetic field lines of a bar magnet The simplest way to trace the magnetic field lines around a bar magnet is by using a compass 1- Place the bar magnet in a piece of paper U.5_6 d16

  17. 5.6.2.a. Magnetic field vectors and magnetic field lines of a bar magnet 1- Place the bar magnet in a piece of paper 2- Next draw a dot anywhere near the magnet and place the compass over the dot. U.5_6 d17

  18. Magnetic field lines of a bar magnet 1- Place the bar magnet in a piece of paper 2- Next draw a dot anywhere near the magnet and place the compass over the dot. 3- Observe the direction of the compass needle and draw a dot at the North Pole and South Pole of the needle 4- Repeat the procedure for different positions U.5_6 d18

  19. Magnetic field lines of a bar magnet 4- Repeat the procedure for different positions 5- Connect the dots and mark the direction of the compass with an arrow U.5_6 d19

  20. Magnetic field lines of a bar magnet Results: To analize the results: Answer the following questions and make your conclusions: U.5_6 d20

  21. Magnetic field vectors of a bar magnet Results: 1.- What is the direction of the magnetic field at any point? U.5_6 d21

  22. Magnetic field vectors of a bar magnet 1.- What is the direction of the magnetic field at any point? https://archive.cnx.org/specials/92176000-ae74-11e5-baad-cfab91c15075/magnets-and-electromagnets/#sim-bar-magnet Simulator U.5_6 d22

  23. 5.6.2.a. Magnetic field vectors and magnetic field lines of a bar magnet If you locate a compass in different places, you will notice that the direction of the magnetic field is always tangent to the magnetic field line U.5_6 d23

  24. 5.6.2.a. Magnetic field vectors and magnetic field lines of a bar magnet Results: Answer the following questions and make your conclusions: 2.- Notice that when the needle of the compass is closer to the magnet, it turns back more quickly, so the field is stronger. Compare the number of field lines in an area close to the magnet and strengh of the field in this area. U.5_6 d24

  25. 5.6.2.a. Magnetic field vectors and magnetic field lines of a bar magnet The density of magnetic field lines is bigger where the magnetic field is greater U.5_6 d25

  26. 5.6.2.a. Magnetic field vectors and magnetic field lines of a bar magnet Results: Answer the following questions and make your conclusions: 3.- Are the magnetic field lines are opened or closed? U.5_6 d26

  27. 5.6.2.a. Magnetic field vectors and magnetic field lines of a bar magnet The magnetic field lines are always closed. They leave the north pole of the magnet and enter at its south pole U.5_6 d27

  28. 5.6.2.a. Magnetic field vectors and magnetic field lines of a bar magnet The magnetic field lines are closed and have no ends. They continue through the interior of the magnet. U.5_6 d28

  29. 5.6.2.a. Magnetic field vectors and magnetic field lines of a bar magnet The magnetic field lines are closed and have no ends. They continue through the interior of the magnet. U.5_6 d29

  30. 5.6.2.a. Magnetic field vectors and magnetic field lines of a bar magnet Conclusions U.5_6 d30

  31. 5.6.2.a. Magnetic field vectors and magnetic field lines of a bar magnet Iron filings experiment You will need: - The bar magnet - The piece of paper - Iron filings Step 1 – Place the magnet under paper Step 2 - Place iron filings onto paper The iron filings onto the piece of paper reveal the magnetic field of the bar magnet. U.5_6 d31

  32. 5.6.2.a. Magnetic field vectors and magnetic field lines of a bar magnet Iron filings experiment U.5_6 d32

  33. 5.6.2.b. Magnetic Field Vectors and Field Lines of two bar magnets • Two bar magnets, unlike poles facing: With more than one magnet, the field lines still start on a north pole and end on a south pole. They start on the north pole of one magnet, and end on the south pole of the other. U.5_6 d33

  34. 5.6.2.b. Magnetic Field Vectors and Field Lines of two bar magnets • Two bar magnets, like poles facing: With two like poles placed nearby, the field lines starting on the north poles curve toward their south poles in order to avoid the north pole of the other magnet U.5_6 d34

  35. 5.6.2.b. Magnetic Field Vectors and Field Lines of two bar magnets Label the poles as N or S, according to the magnetic field lines U.5_6 d35

  36. 5.6.2.b. Magnetic Field Vectors and Field Lines of two bar magnets Label the poles as N or S, according to the magnetic field lines U.5_6 d36

  37. What are the magnetic field lines in these other examples: Horseshoe magnet U.5_6 d37

  38. What are the magnetic field lines in these other examples: U.5_6 d38

  39. 5.6.2.c. Some other magnetic fields • The Magnetic Field of the Earth Why does the north pole of a compass point geographically north? U.5_6 d39

  40. 5.6.2.c. Some other magnetic fields • The Magnetic Field of the Earth Why does the north pole of a compass point geographically north? The geomagnetic north pole is actually a magnetic south (S) pole. It attracs the N pole of a compass The geomagnetic south pole is actually a magnetic north (N) pole. It attracs the S pole of a compass U.5_6 d40

  41. 5.6.2.c. Some other magnetic fields • The Magnetic Field of the Earth U.5_6 d41

  42. 5.6.2.c. Some other magnetic fields • The magnetic field of a flexible refrigerator magnet U.5_6 d42