Magnets and Electromagnets

Transcription

1 Magnets and Electromagnets Y8 Programme of Study JM July 2015! Y8 MAGNETS & ELECTROMAGNETS!1

2 Magnets and Electromagnets Y8 - Scheme of Work Content Copyright Wigmore High School - Physics Dept All rights reserved. No portion of this book may be reproduced, stored in a retrieval system or transmitted at any time or by any means mechanical, electronic, photocopying, recording or otherwise, without prior, written permission of the publisher. The rights of Wigmore High School Physics Dept. to be identified as the author of this work has been asserted by him in accordance with the Copyright, Design and patents act Y8 MAGNETS & ELECTROMAGNETS!2

3 ! Magnets and Electromagnets Lesson Title Page 1 Why does the paper clip Levitate? 4 2 What shape is the Field around the magnet? 6 Optional How to make a Magnetic puzzle? 8 4 How can you tell if something is a Magnet? Research 7 Can we make a magnet and what are the benefits? How do MagLev trains work? Explain the use of magnets and the benefits from using them? Can we make a simple electric motor using magnets? How can we use Electromagnets? 18 9 Physics Magnetism Challenge Magnets and Electromagnets Assessment Version July 2015 Y8 MAGNETS & ELECTROMAGNETS!3

4 Lesson 1/10 Why does the paper clip Levitate? Learning Objective: Students be able define: that a magnetic fields is a regions of space where magnetic materials experience forces. Learning Outcome: Students should: know that around a magnet certain materials experience a force. know that only cobalt, nickel, iron and their alloys are magnetic materials. know that magnetic force can pass through non magnetic materials. know that magnetic force attracts magnetic materials. know that magnetism is a strong non contact force. Prior Knowledge: Building on KS3: Forces Y7 Assessment: H/wk: Links: Compasses Georgaphy Earth as a magnet. Vocabulary: Magnetism, magnetic field, non-contact force, magnetic material, non-magnetic material, alloy Safety: General class rules Y8 MAGNETS & ELECTROMAGNETS!4

5 Activities: Heading: Why does the paper clip levitate? Class activities: 1. Show pupils how to set up their levitating paper clip. 2. Discuss why the paper clip is levitating. 3. Get the pupils to pass different materials through the gap and describe if there is any effect. 4. Ask about the two pence pieces? Student activities: i. Set up experiment. Draw a diagram labelling where appropriate. ii. Make a table and collect results for materials tried. iii. Identify those materials that have an effect. iv. On their diagram add a description using all the vocabulary. Teacher note: Attach thread to paper clip sellotape opposite end of thread to table. Place magnet on clamp stand attach paper clip. Push stand away till paper clip levitating. Technician: Magnets Thin sheets of material to include iron, nickel, cobalt. Thread Scissors Cellotape Paper clips Clamp stands Lots of 2p pieces old and new. Y8 MAGNETS & ELECTROMAGNETS!5

6 Lesson 2/10 What shape is the Field around the Magnet? Learning Objective: Students be able to: about magnetic fields as regions of space where magnetic materials experience forces and the field pattern produced by a bar magnet. Learning Outcome: Students be able to: describe the magnetic field around a magnet. show that a magnetic field has direction. show what happens to the force lines when two poles are close together. Prior Knowledge: Building on KS3: Forces Y7 Assessment: H/wk: Links: To pole moving and so iron crystals in rocks changing direction link with sea floor spreading. Vocabulary: Magnetic field lines, compass, magnetic pole. North, south, north seeking south seeking. field, force Safety: General class rules Y8 MAGNETS & ELECTROMAGNETS!6

7 Activities: Heading: What shape is the Field around the Magnet? Class activities: 1. Introduce the practical and idea of the field around magnet. 2. When complete show the field has direction by using a compass. 3. Discuss the idea that the magnetic force has direction and that the Earth is a magnet and we use North and South seeking magnets as compasses. At the poles the compass is useless as field lines go almost vertically. Student activities: i. Carry out practical finding shape of field. ii. Add the direction of the magnetic field around the magnet using plotting compasses. iii. Add some notes to their diagram. iv. Attempt to see the pattern between the different poles NN, SS, SN. v. Add these to their diagram. Teacher note: Draw around magnet on A4 paper mark poles. Place magnet between two exercise books put paper on top with magnet. Scatter iron fillings tap gently on paper. Draw pattern. Remove iron filings and use plotting compass to get field line direction Might want a clip of Northern Lights Make a ferro liquid magnet v=vsqh1at6que Technician: a. Magnet set b. A4 plain paper c. Iron fillings d. Compasses e. Globe Y8 MAGNETS & ELECTROMAGNETS!7

8 Lesson Optional/10 How to make a Magnetic Puzzle? Learning Objective: Students should: understand that even common place examples have a scientific basis. be able to describe the Science behind a simple puzzle. apply knowledge and language to a new situation Learning Outcome: Students should be able to: build a working toy. describe for an audience of children how the toy works. use appropriate and correct vocabulary. Prior Knowledge: Builds on KS3: Y7 Forces Assessment: H/wk: Take home their toy and describe how it works to a family member. Links: How scientific ideas make their way into everyday lives. Vocabulary: Magnet. Magnetic field, magnetic material, non magnetic material, non contact force. Safety: Iron fillings getting every where! Y8 MAGNETS & ELECTROMAGNETS!8

9 Activities: Heading: How to make a Magnetic Puzzle? Class activities: 1. Introduce the toy that they can make. 2. Make a poster explaining the Science behind the Puzzle. Student activities: Make puzzle. Design a poster using all the vocabulary. Feedbak to class your puzzle and poster. Technician: Old petri dishes. Cellotape Scissors. Glue Iron fillings Magnets Y8 MAGNETS & ELECTROMAGNETS!9

10 Lesson 4/10 How can you tell if something is a magnet? Learning Objective: Students should know that: that similar poles repel that opposite poles attract. that magnetic materials are aways attracted. that magnets are identified by them being repelled by another magnet. that magnetic materials can become magnetic. Learning Outcome: Students should: know how magnetic poles interact. know how to identify another magnet. know that a magnetic material can become magnetised understand that the force increases with proximity Prior Knowledge: Build on KS3: Assessment: H/wk: Links: Vocabulary: Simple domain model, repel, attract, magnetic poles, hard magnetic material, soft magnetic material, demagnetise, induced poles, non-contact force. Safety: General class rules Y8 MAGNETS & ELECTROMAGNETS!10

11 Activities: Heading: How can you tell if something is a magnet? Class activities: 1. Introduce and look at magnets repelling and attracting. Discuss how you can separate a magnet from a magnetic material. 2. Understand that the force is much stronger the closer together the magnetic to the other magnet or magnetic material. 3. Show the force using a balance an magnet above a iron object. Student activities: i. Play with magnets and look at how the forces on the poles interact. ii. Sketch a table / graph to show the effect of the proximity of the magnet to the iron object on the balance. What does this show iii. Make a interactive poster to show how two magnets either repel or attract. Teacher notes: Draw one magnet other magnet free to move with split pin. as it spins around should say either repel or attract as appropriate. Technician: A5 card + strips of card to represent a magnet Magnets, Scissors, Glue Split pins, Craft knife and board possibly 333 balance Big iron nail or something like that Card Arrows different sizes Big one with weight on, one same size as this and a few getting smaller with magnetic force on them. Y8 MAGNETS & ELECTROMAGNETS!11

12 Lesson 5/10 benefits? Can we make a magnet and what are the Learning Objective: Students be able to: can describe how to make an electromagnet. describe how to make a magnetic field stronger or weaker around a electromagnet. Learning Outcome: Students be able to: describe the magnetic field around a wire when it is carrying a current. describe how coiling the wire gathers these magnetic fields together. identify suitable core material to use inside the coil. explain why we use a soft iron core. describe how the current strength might affect the magnet field strength. explain how to alter the strength of the magnetic field around the electromagnet. describe the benefits of electromagnets. Prior Knowledge: Builds on KS3: Y7 Electrical Circuits Assessment: H/wk: Links: Vocabulary: Electromagnet, coil, core, induction, current, voltage, solenoid, right hand grip rule, laminated. Safety: Wires can be come hot sometimes. Y8 MAGNETS & ELECTROMAGNETS!12

13 Activities: Heading: Can we make a magnet and what are the benefits? Class activities: 1) Show that when a current flows through a wire; the wire has a magnetic field around it. If the current changes direction so does the magnetic field. 2) Show that coiling the wire allows the magnetic field to reinforce itself. Pupils can role play the wire in the coil pointing in the direction of flow. 3) Introduce the idea of a core. Let pupils experiment with different cores different number of coils. 4) Discuss the benefits of the electromagnets. Student activities: i. Make some diagrams of the magnetic field in a wire. ii. Make a diagram of wire and magnetic field in a coil. iii. Make some electromagnets experimenting with different cores the different numbers of coils. (Make a prediction) iv. Write down or draw your conclusions. v. Write down some benefits of electromagnets. Technician: Power packs 2v ones for electromagnets. Wire Caples and clips Wire strippers pliers Different straight cores. Y8 MAGNETS & ELECTROMAGNETS!13

14 Lesson 6/10 How do MagLev trains work? Explain the use of magnets and the benefits from using them? Learning Objective: Students should: Write in appropriate English use literacy skills Improve research skills and use of 2 y sources show understanding of magnets reeling and attracting show understanding of how electromagnets ca be controlled Learning Outcome: Students should be able to: write a prose passage on a science topic. structure writing to inform and audience and how understanding. understand why magnets are used in MagLev trains. Prior Knowledge: Builds on KS3: Y7 Forces Assessment: Piece of work produced is assessment for this lesson. H/wk: Links: Literacy, research Vocabulary: Own selection but should be highlighted. Safety: General Y8 MAGNETS & ELECTROMAGNETS!14

15 Activities: Heading: How do MagLev trains work? Explain the use of magnets and the benefits from using them? Class activities: 1. Introduce research topic 2. Give suggested websites Student activities: Initial research bullet points draft report finalise report print off and stick in books. Technician: ICT room needed Glue sticks Y8 MAGNETS & ELECTROMAGNETS!15

16 Lesson 7/10 using magnets? Can we make a simple electric motor Learning Objective: Students should: be able to simply explain how a simple DC electric motor works. Learning Outcome: Students should be able to: explain how to make a simple DC electric motor. explain the effect of increasing the current in the coil on the motor (turning effect). explain the effect on the motor (turning effect) of increasing the size of coil. explain the effect on the motor (turning effect) of increasing the size of coil. Prior Knowledge: Builds on KS3: Y7 Forces Assessment: H/wk: Links: Vocabulary: DC, coil, commutator (mention only), brushes, electromagnet, permanent magnet. Safety: Y8 MAGNETS & ELECTROMAGNETS!16

17 Activities: Heading: magnets? Can we make a simple electric motor using Class activities: 1. Discuss what happens when poles interact? What happens if one is able to move? What if it can move and change it s magnetic field? 2. Show simplified model, electric motor large to show. 3. Explain how to make simple dc electric motor. Student activities: Draw simple diagram of a simple dc electric motor. Make motor. Technician: Electric motor kits. simple model of motor. wire strippers and snips. Y8 MAGNETS & ELECTROMAGNETS!17

18 Lesson 8/10 How can we use Electromagnets? Learning Objective: Students should: know that electromagnets (relays) can be used in a range of situations. know that electromagnets (relays) can be used as switches. investigate the use of electromagnets (relays). know that electromagnets can be used to change the voltage. Learning Outcome: Students should be able to: know that an electromagnets (relays) can be used to switch on an alternative power supply. know that an electromagnets (relays) can be used to safely control large voltages. draw circuit diagrams for the above circuits. explain how an electric bell works. know that electromagnets can have their poles swapped if you change the current direction Prior Knowledge: Builds on KS3: Y7 Forces Assessment: H/wk: Links:. Vocabulary: Electromagnets, relays, circuit diagram, generator, transformer, primary coil, secondary coil, C core, laminated, robotics. Safety: Y8 MAGNETS & ELECTROMAGNETS!18

19 Activities: Heading: How can we use Electromagnets? Class activities: 1. Robot fish look at inside, put in water explain how it swims. Use compass to show it is magnetic. 2. Use an electric bell explaining how the electromagnet controls the ringing. 3. Use a relay to switch on a second circuit, discuss possible uses and circuit diagrams. 4. Get students toddling their own system to switch on a secondary circuit. 5. Show transformer what is happening show that C cores can be separated by paper. Student activities: Explain how robot fish works Draw circuits and explain how the bell works Explain how they could use an electromagnet to turn on a secondary circuit. Make a simple explanation of how transformer works. Technician: Relays Crocodile clips Cables Power supply (2V and 12V) Bulbs and holders Buzzers Multi meter Extension cable to demo on front bench Fish (clear) tank filled with water. Robot fish and compass Y8 MAGNETS & ELECTROMAGNETS!19

20 Lesson 9/10 Thinking about Physics Magnetism Challenge Learning Objective: Students should: use science knowledge in a practical situation show understanding of science knowledge and how to apply it. Learning Outcome: Students should be able to: correctly choose of magnet for the task. correctly choose of vocabulary justify their choices Prior Knowledge: Builds on KS3: Y7 Forces Assessment: Piece of work produced is assessment for this lesson. H/wk: Links: Vocabulary: Own selection but should be highlighted. Safety: General Y8 MAGNETS & ELECTROMAGNETS!20

21 Activities: Heading: Thinking about Physics Magnetism Challenge Class activities: 1. Introduce Challenge Student activities: Complete challenge Technician: Magnets Electromagnets made up (both straight and horse shoe) 2V power packs Aluminium and steel cans in a tray String Wire A3 plane paper Y8 MAGNETS & ELECTROMAGNETS!21

22 Vocabulary Alloy: Not a pure metal a mixture. Alternating current (ac): An electric current that flows one way then the other, think of a swing. Attract: Where an object is drawn to another. Brushes: Electrical connector than still contact even if something is moving, Skalextric connectors. C core: The laminated core you find in transformers. As it is C shaped. Circuit diagram: A diagram of a circuit where wires are straight lines and components have symbols. Coil: Wire neatly wrapped. Commutator (mention only): Where a wire has to spin and keep contact with the power sources see brushes used in electric motors. Compass: A navigation device reliant on the Earth s magnetic poles. Has a N and S seeking end. Core: A metal in the centre of a coil of wire that improves the strength of the magnetic field. Current: Flow of electrons in a wire or metal. Demagnetise: Where dropping banging heating a permanent magnet makes it lose its magnetism. Diamagnetc: A material that is repelled by a magnet. Not covered at GCSE. Direct current (dc): An electric current that only flows in one direction. Electromagnet: A magnet formed from electricity flowing through a coiled wire often with an iron core. Electromagnetic induction: Where electricity induces makes a magnetic field and where a magnetic field can induce an electric current. Field: Area around an object that is influenced by that object, e.g. magnet; area around where the magnet can affect other objects. Force: Can have an influence over another object causing it to possibly move. Generator: A device that can produce electricity from moving magnets and coils. Hard magnetic material: A material that once magnetised tends to stay magnetised. Induced poles: The poles that you get on an electromagnet, just like a bar magnet. Induction: Where one object had an effect on another object. Laminated: Cores are laminated (made up of thin layers) to prevent too much heat being generated and so reduce energy loss. Magnet: More properly a permanent magnet, has ability to repel or attract other magnets and attract magnetic materials. Magnetic field: Area around the magnet that can affect other objects. Magnetic field line: Part of the field where the effect is strongest, where the iron fillings gather. Y8 MAGNETS & ELECTROMAGNETS!22

23 Magnetic material: Material attracted to a magnet. Either N or S pole. Magnetic pole: End of the magnet where the field lines emerge or enter the magnet. Magnetism: Force associated with magnets. Non contact force: A force that does not need to touch the object being effected. Non magnetic material: Not affected by a magnetic field. North: Pole of a magnet here the field lines emanate. North seeking: A magnet that is attracted to the North pole of a magnet and Earth Permanent magnet: A magnet that maintains it s magnetism unless demagnetised. Primary coil: The coil on a transformer that takes the input current / voltage. Relays: Electromagnetic devices for controlling switches. Repel: Push away. Right hand grip rule: Rule to establish the direction of a magnetic field around a wire, and the poles of a electromagnet. Robotics: Is the branch of mechanical engineering, electrical engineering and computer science that deals with the design, construction, operation, and application of robots, as well as computer systems for their control, sensory feedback, and information processing. Secondary coil: Coil that produces the output voltage / current in a transformer. Simple domain model: Idea that magnetism is made up of little packets of localised magnetism. When these align then the object becomes more magnetic. Soft magnetic material: A material that tends not remain magnetic when part of an electromagnet, after it is switched off. Solenoid: Name for an electromagnet. South: End of magnet where field lines re-enter. South seeking: A magnet that is attracted to the South pole of a magnet and Earth Transformer: A machine using electromagnetic induction to increase or decrease the voltage / current of an electrical supply. Voltage: Essentially the amount of energy that an electrical source can supply. Y8 MAGNETS & ELECTROMAGNETS!23

24 Learning Outcome: By the end of this topic students should: know that around a magnet certain materials experience a force. know that only cobalt, nickel, iron and their alloys are magnetic materials. know that magnetic force can pass through non magnetic materials. know that magnetic force attracts magnetic materials. know that magnetism is a strong non contact force. describe the magnetic field around a magnet. show that a magnetic field has direction. show what happens to the force lines when two poles are close together. know how magnetic poles interact. know how to identify another magnet. know that a magnetic material can become magnetised understand that the force increases with proximity describe the magnetic field around a wire when it is carrying a current. describe how coiling the wire gathers these magnetic fields together. identify suitable core material to use inside the coil. describe how the current strength might affect the magnet field strength. explain how to alter the strength of the magnetic field around the electromagnet. describe the benefits of electromagnets. explain why we use a soft iron core explain how to make a simple DC electric motor. explain the effect of increasing the current in the coil on the motor (turning effect). explain the effect on the motor (turning effect) of increasing the size of coil. explain the effect on the motor (turning effect) of increasing the size of coil. know that an electromagnets (relays) can be used to switch on an alternative power supply. know that an electromagnets (relays) can be used to safely control large voltages. Y8 MAGNETS & ELECTROMAGNETS!24

25 know that electromagnets can have their poles swapped if you change the current direction draw circuit diagrams for the above circuits explain how an electric bell works. write a prose passage on a science topic. structure writing to inform and audience and how understanding. understand why magnets are used in MagLev trains. Useful Websites: BBC new Bitesize and resources Y8 MAGNETS & ELECTROMAGNETS!25