6 Magnetism and Electromagnetism Part C 1 Electromagnetism

  • Slides: 51
Download presentation
6 Magnetism and Electromagnetism “Part C 1 – Electromagnetism Solenoids and Fields” 1 Forces

6 Magnetism and Electromagnetism “Part C 1 – Electromagnetism Solenoids and Fields” 1 Forces and Motion 5 Solid Liquids Gases 2 Electricity 6 Magnetism Lesson 2 - Compasses and Magnetic Fields Lesson 3 - The magnetic effect of a solenoid Lesson 4 - Electromagnets in Action 3 Waves 7 Radioactivity i. GCSE Edexcel 1 -9 – Mr Powell 4 Energy 8 Astrophysics Animated Science 2020

6 Electromagnetism “Part C - 1 and 2” 6. 8 know that an electric

6 Electromagnetism “Part C - 1 and 2” 6. 8 know that an electric current in a conductor produces a magnetic field around it 6. 9 P describe the construction of electromagnets (Triple) 6. 10 P draw magnetic field patterns for a straight wire, a flat circular coil and a solenoid when each is carrying a current (Triple) 6. 13 use the left-hand rule to predict the direction of the resulting force when a wire carries a current perpendicular to a magnetic field -------------- Next Part… 6. 11 P know that there is a force on a charged particle when it moves in a magnetic field as long as its motion is not parallel to the field (Triple) 6. 12 understand why a force is exerted on a current-carrying wire in a magnetic field, and how this effect is applied in simple d. c. electric motors and loudspeakers 6. 14 describe how the force on a current-carrying conductor in a magnetic field increases with the magnitude and direction of the field and current. Animated Science 2020

6 Electromagnetism “Part C - 1 and 2” Key Topic Aims…. (Recall & Apply

6 Electromagnetism “Part C - 1 and 2” Key Topic Aims…. (Recall & Apply ideas and formulae) 6. 8 know that an electric current in a conductor produces a magnetic field around it 6. 9 P describe the construction of electromagnets (Triple) 6. 10 P draw magnetic field patterns for a straight wire, a flat circular coil and a solenoid when each is carrying a current (Triple) 6. 13 use the left-hand rule to predict the direction of the resulting force when a wire carries a current perpendicular to a magnetic field ---------------------------6. 11 P know that there is a force on a charged particle when it moves in a magnetic field as long as its motion is not parallel to the field (Triple) 6. 12 understand why a force is exerted on a currentcarrying wire in a magnetic field, and how this effect is applied in simple d. c. electric motors and loudspeakers 6. 14 describe how the force on a current-carrying conductor in a magnetic field increases with the magnitude and direction of the field and current.

Collins Textbook – Notes Task… Magnets and Right Hand Grip Rule p 294 -310

Collins Textbook – Notes Task… Magnets and Right Hand Grip Rule p 294 -310 Tasks… • p 294/5 – read/ note key symbols and quantities. Add Magnetic Field – Tesla “B” for Tesla to your list. • p 296 – write a definition and application for “Hard or Soft” magnetism • p 297 – draw and explain the field lines for a standard NS field and explain how a plotting compass can be used to show a field. • p 298 - draw and explain the field lines for the planet Earth. • p 201 – draw and explain the field lines for the 2 nd two diagrams SS and NS SN arrangements / p 303 Fig 6. 11 • p 306 -8 Explain a simple practical for investigating fields for an electromagnet. • p 309/10 – use the images given to you (OR draw your own) to explain the right hand grip rule and how it works for a solenoid. Animated Science 2020

Animated Science 2020 Mr D Powell 2020 Lesson 2 Compasses and Magnetic Fields (30

Animated Science 2020 Mr D Powell 2020 Lesson 2 Compasses and Magnetic Fields (30 mins) I know the direction of the Earth’s magnetic field. 4 I can describe the magnetic field due to a current in a wire 5/6 I can explain the link between current and magnetic field. 7/8 I can plan an experiment to investigate the field around a wire Animated Science 2020

Do Now Task. . From last lesson try and explain what happens here. 1)

Do Now Task. . From last lesson try and explain what happens here. 1) Name the effect 2) Explain why the first nail is attracted to the magnet 3) Explain why the nails magnetise other nails? 4) There is a special name for this process (from 3) Animated Science 2020

The Earth’s core acts as a giant magnet but confused…. . Clearly the North

The Earth’s core acts as a giant magnet but confused…. . Clearly the North Geographic pole is actually a Magnetic South as it attracts the North pole on a magnet. Red is often used for a North Magnetic Pole. This is clear evidence that the Earth has a field. However, the magnet does not really exist as the inside of the earth is hot and semi liquid. More complex things are going on inside. The density of lines at the poles shows how the field is strong at the poles. Steel bridges and structures can at times become magnetic by the “induction” of the field from the Earth but it is usually a weak effect. Animated Science 2020

Lesson 2 Compasses and Magnetic Fields 2 A magnetic compass points away from the

Lesson 2 Compasses and Magnetic Fields 2 A magnetic compass points away from the geographic south pole so the polarity of the geographic south pole is actually north. 3 It seeks out (i. e. points towards) the Earth’s North Pole. Animated Science 2020

Lesson 2 Compasses and Magnetic Fields 4) If the current is reversed direction, can

Lesson 2 Compasses and Magnetic Fields 4) If the current is reversed direction, can you sketch how the sheet of paper would look. Do your drawing in 2 d. 5) Sketch a diagram to show what would happen if you had the original current flow but the potential difference was now 4 V 6) Explain why a compass placed right on the edge might not show the field lines clearly? 6 The magnetic field produced by the current is very weak and it is even weaker the further you are from the wire. Therefore, a compass towards the edge of the card will be affected by the Earth’s magnetic field as much as the wire’s and may deviate. Animated Science 2020

Animated Science 2020 Mr D Powell 2020 Lesson 3 The magnetic effect of a

Animated Science 2020 Mr D Powell 2020 Lesson 3 The magnetic effect of a solenoid I can draw the magnetic field around a conducting wire and a solenoid. 4 I can describe the force on a wire in a magnetic field. 5/6 7/8 I can apply the left-hand rule to work out the direction of a magnetic field, a current or a force around a wire. I can apply these ideas to a wider variety of situations using the Anticlockwise and Clockwise ideas with confidence. Animated Science 2020

The Right-Hand Grip Rule 1. The right hand grip rule shows that when a

The Right-Hand Grip Rule 1. The right hand grip rule shows that when a current flows in a wire, it will produce a magnetic field with direction as shown. 2. In SI units, B is measured in teslas (symbol: T) correspondingly. Key Points… Task… • For a higher current flow, the larger the field. 1. Review the information shown • The larger the radius (distance from field) the smaller the field strength is. • If you reverse the current you reverse the direction of the field. 2. You may discuss with a partner the ideas shown AND with your teacher. 3. Write a short note of the key points for each idea in the space provided Animated Science 2020

Fields Around Solenoids Key Points… • Each loop of wire has a field around

Fields Around Solenoids Key Points… • Each loop of wire has a field around it. • You don’t see the circular fields but the overall effect… • Several loops add their fields on each side to produce an effect similar to a bar magnet. • Which is controlled by the current and can be made stronger by using an iron core. Rule to learn is. . . North pole - a. Nticlockwise South pole – Clockwise • A bar magnet can be passed through a coil and induce a current to flow (as a reverse effect) Animated Science 2020

Spaced Learning Review Question Task 1… Answer the questions on your own – write

Spaced Learning Review Question Task 1… Answer the questions on your own – write a clear answer and number in your book. Get as far as you can in the time you have…. Electromagnets / Solenoids Animated Science 2020

Spaced Learning Review Answers Task 2… Mark your work in green pen, you can

Spaced Learning Review Answers Task 2… Mark your work in green pen, you can judge how you did, put a clear total at the bottom and put one clear comment on what you must improve on. Electromagnets / Solenoids Animated Science 2020

Hard or Soft Magnets – Recap! Iron, nickel and cobalt are the only pure

Hard or Soft Magnets – Recap! Iron, nickel and cobalt are the only pure metals that can be turned into a permanent magnet. Steel is an alloy of iron and so can also be made into a magnet. Metals that are permanently magnetised are described as magnetically hard (often alloys with lots of iron, nickel and cobalt or stainless steel). If a material is temporarily magnetised it is described as magnetically soft. Alloys with less iron, nickel or cobalt will be magnetically soft and have a weaker magnetic field. Often iron is used in transformers OR electromagnets in car breakers yard. As it is “magnetically soft” so it can demagnetise easily without getting very hot. Alloys of iron are called ferrous and those without iron are called non-ferrous. Ni Co Fe Animated Science 2020

Lesson 3 The Magnetic Effect of a Solenoid – Practical / Analysis Equipment… •

Lesson 3 The Magnetic Effect of a Solenoid – Practical / Analysis Equipment… • • • d. c. power supply (2 V Approx or it will trip) Wire (thick and rigid) Cylinder (i. e. glue stick) Piece of cardboard with slits/ holes cut into it Plotting compass Croc Clips OR connectors Method 1. 2. 3. 4. 5. 6. 7. Connect the wire to the power supply. Wind the wire around the cylinder 5 times. Slide the cylinder with the wire on it into the slits in the cardboard. Remove the cylinder but leave the coil of wire. Turn on the power and place the plotting compass around the coil and inside the coil. Use the 3 D magnaprobe if you have one If you have iron filings, you can also sprinkle them around the solenoid to determine the shape of the magnetic field around it. Questions: Is there a difference in the shape of the field if you reverse the current and what do you find? Direction of Force (N) Magnetic Flux Density (B) Conventional Current (I) + to - Animated Science 2020

Learning Flemings Left-hand Rule The magnetic field produced around the wire due to the

Learning Flemings Left-hand Rule The magnetic field produced around the wire due to the current flow interacts with the field across the jaws of the horseshoe magnet. It pushes the wire out of the field according to the “Left Hand Rule”. Which is very easy to remember using the mnemonic of FBI. If all three are at 90 you get a maximum force or push. This is sometimes called the “motor effect” or a catapult field. F = Force (N) B = Magnetic Field (T) I = Conventional Current Flow (A) Direction of Force (N) Magnetic Flux Density (B) Don ’t S hoo t! Conventional Current (I) + to Animated Science 2020

3 When a conductor carrying an electric current is placed in a magnetic field

3 When a conductor carrying an electric current is placed in a magnetic field a force may act on it. a) State two ways in which this force can be increased. 1. . . . . . 2. . . . . . b) State two ways in which this force can be made to act in the opposite direction. 1. . . . . . 1) Explain what this rule means / 2) Label the force for each case: . . . . . . 2. . . . . . . . . . . . . c) In what circumstance will no force act on a conductor carrying an electric current and in a magnetic field? . . . . . . . . . . . . . a) b) . . . . . . 4) Action c) d) Effect on the size of Effect on the direction the force of the force Using stronger magnets Decreasing the current Using a longer wire Changing the direction of the current Swapping the poles of the magnet around Animated Science 2020

3 When a conductor carrying an electric current is placed in a magnetic field

3 When a conductor carrying an electric current is placed in a magnetic field a force may act on it. a) State two ways in which this force can be increased. Larger magnetic field (T) 1. . . . . . Larger current flow (A) 2. . . . . . b) State two ways in which this force can be made to act in the opposite direction. 1. . . . . . Reverse the current flow (A) 1) Explain what this rule means / 2) Label the force for each case: 2. . . . . . Reverse the magnetic field (T) . . . . . . When a field and current act at 90 degrees. . . . . . . they produce a directional force on the wire c) In what circumstance will no force act on a conductor carrying an electric current and in a magnetic field? . . . . . . . . . . . . . If the conductor is parallel to the field a) or current and magnetic field is not at. . . . . . b) 90 (crossed) 4) Action c) d) Effect on the size of Effect on the direction the force of the force Using stronger magnets Up no Decreasing the current Down no Using a longer wire Up no No reverse Changing the direction of the current Swapping the poles of the magnet around no Animated Science reverse 2020

Flemings Left Hand Rule Review… Action Task… try this on a whiteboard OR worksheet

Flemings Left Hand Rule Review… Action Task… try this on a whiteboard OR worksheet Effect on the size of the Effect on the direction of force the force Using stronger magnets Decreasing the current Using a longer wire Changing the direction of the current Swapping the poles of the magnet around Animated Science 2020

Flemings Left Hand Rule Review… Action Using stronger magnets Decreasing the current Using a

Flemings Left Hand Rule Review… Action Using stronger magnets Decreasing the current Using a longer wire Changing the direction of the current Swapping the poles of the magnet around Task… try this on a whiteboard Effect on the size of the Effect on the direction of force the force Increases the size of the force Decreases the size of the force Increases the size of the force No effect No effect Changes the direction of the force Animated Science 2020

Complex View of why it goes left or right! N If you cannot remember

Complex View of why it goes left or right! N If you cannot remember the rule you can work out the situations from the first principles of conflicting magnetic fields and the right hand grip rule. The diagrams clearly show on one side the fields cancel and on the other they add. This addition creates a motion left or right (on the diagrams). S Try using the LHR and RH Grip rule to work it out… N Direction of Force (N) Magnetic Flux Density (B) Conventional Current (I) + to - S https: //youtu. be/U 9 Rezs. Wn. PYs Animated Science 2020

Lesson 3 The magnetic effect of a solenoid 1) If you reverse the flow

Lesson 3 The magnetic effect of a solenoid 1) If you reverse the flow of current in a solenoid, what happens to the direction of the field? 2) If you look at the end of a solenoid and note that the current is going in a clockwise direction. What is the pole at that end? 3) Suggest three things that would make an electromagnet stronger? Rule to learn is. . . North pole - a. Nticlockwise South pole – Clockwise 1. The magnetic field is in the opposite direction. 2. The south pole (see the image) North is a. Nti 3. Increase the number of turns of wire OR the current; place iron inside the coil to reinforce the field. Animated Science 2020

Lesson 3 The magnetic effect of a solenoid 4) A wire is placed in

Lesson 3 The magnetic effect of a solenoid 4) A wire is placed in a magnetic field at right angles. When an electrical current flows the wire moves to the up. a) b) Which way does the wire move when the current direction is switched? What happens if we now reverse the current flow? 5) Explain how you can decrease the force on the wire? 4 a Downwards 4 b Assuming the current is in the original direction, the wire moves down. If the current remains reversed, then the wire would move to the up. 5) You could reduce the current or reduce the strength of the magnetic field by using a weaker magnet. Animated Science 2020

Do Now Task. . Using this image. . . 1. can you explain how

Do Now Task. . Using this image. . . 1. can you explain how Flemings Left Hand Rule works to the person next to you. 2. The go on to explain what happens if you reverse the field or the current to the direction of motion. 3. Can you remember a cool mnemonics for remembering the LHR in an exam – name each variable in detail! Animated Science 2020

Spaced Learning Review Question Task 1… Answer the questions on your own – write

Spaced Learning Review Question Task 1… Answer the questions on your own – write a clear answer and number in your book. Get as far as you can in the time you have…. Flemings Left Hand Rule… Animated Science 2020

Spaced Learning Review Answers Task 2… Mark your work in green pen, you can

Spaced Learning Review Answers Task 2… Mark your work in green pen, you can judge how you did, put a clear total at the bottom and put one clear comment on what you must improve on. Flemings Left Hand Rule… Animated Science 2020

Animated Science 2020 Mr D Powell 2020 4 Lesson 4 Electromagnets in Action (1

Animated Science 2020 Mr D Powell 2020 4 Lesson 4 Electromagnets in Action (1 hour) I can describe simple uses and benefits of electromagnets such as picking up a car AND make an electromagnet 5/6 + I can explain how an electric bell and relay work in detail and explain the variables involved in an electromagnet 7/8 +I can interpret diagrams of other devices that use electromagnets to explain how the devices work such as a relay. I can investigate an electromagnetic field around a solenoid with the magnaprobe to explain how the field looks in 3 D Animated Science 2020

What uses could you have for an electromagnet Task: Discuss how these might work?

What uses could you have for an electromagnet Task: Discuss how these might work? Animated Science 2020

Quick Exam Question – Draw 1 example diagram then copy & complete the questions…

Quick Exam Question – Draw 1 example diagram then copy & complete the questions… A A student is investigating the strength of electromagnets. The images show three electromagnets. The student hung a line of paper clips from each electromagnet by induced magnetism. 1) Increasing the number of turns of wire wrapped around the nail will ______ the strength of the electromagnet. (1) B 2) Which two pairs of electromagnets should be compared to make this conclusion and why? Pair 1: ___ & ___ Reason_____(1) Pair 2: ___ & ___ Reason_____(1) C 3) Suggest two control variables in this investigation and explain why…… Variable 1: ___ & ___Reason__________(1) Animated Science 2020

Quick Exam Question – Draw a diagram then copy & complete the questions… Answers….

Quick Exam Question – Draw a diagram then copy & complete the questions… Answers…. A 1) Increase A student is investigating the strength of electromagnets. The images show three electromagnets. The student hung 2) A and B - same current flow a line of paper clips from each electromagnet by induced B and C – same number of turns magnetism. 3) size of nail / material / current 1) Increasing the number of turns of wire wrapped around / cell / p. d / paper clip size / the nail will ______ the strength of the length of wire / thickness of wire. B electromagnet. (1) 2) Which two pairs of electromagnets should be compared to make this conclusion and why? Pair 1: ___ & ___ Reason_____(1) Key Questions…. 1. What is the key Science you have learned OR recalled C 3) Suggest two control variables in this investigation andhere? explain why…… 2. What key Science terms are Variable 1: ___ & ___Reason_____(1) relevant to this question & why? (use terms sheet) Variable 1: ___ & ___Reason_____(1) Pair 2: ___ & ___ Reason_____(1) Animated Science 2020

Making an Electromagnet – Practical Equipment… (per pair) • • • Soft iron core

Making an Electromagnet – Practical Equipment… (per pair) • • • Soft iron core Thin wire with insulation D. C. power pack 0 -12 V Two croc clips Pot of paperclips Task… 1. Using the diagram shown to create your own electromagnet and feel the force from the B-Field! 2. Test it using paperclips & other metals (i. e. from your own pencil case – remember Cobalt, Nickel, Iron and Steel!) 3. Vary the DC power and turns to see what happens. 4. Use the magnetic probe to test the field direction and strength in 3 D (if you have one) 5. Repeat without the core! 6. Write up your findings simply in your book. Animated Science 2020

Lesson 4 Electromagnets in Action – Worksheet – Task 1 Equipment… (per pair) •

Lesson 4 Electromagnets in Action – Worksheet – Task 1 Equipment… (per pair) • • • Soft iron core Thin wire with insulation D. C. power pack 0 -12 V (don’t trip it!) Two croc clips Pot of paperclips Magnaprobe Task 1… 1. 2. 3. 4. 5. 6. 7. Using the diagram shown to create your own electromagnet and feel the force from the B-Field! Draw a simple circuit diagram in the space provided (Basic) Add an Ammeter if you can (0 to 10 A) Test it using paperclips & other metals (i. e. from your own pencil case – remember Cobalt, Nickel, Iron and Steel!) Vary the DC power and turns to see what happens. (Harder) Use the magnetic probe to test the field direction and strength in 3 D Write up your findings simply on this sheet and/ OR your book. Are your results proportional? Extension… Repeat without the core and try the same linking to the direction from a previous lesson! Rule to learn is. . . North pole - a. Nticlockwise South pole – Clockwise Circuit Diagram / Magnetic Field Sketch…. (draw at 90 if you run out of space) My Observations / Variables…. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Animated Science 2020

Circuit Diagrams for Alarm Bell • Explain the steps that are involved in how

Circuit Diagrams for Alarm Bell • Explain the steps that are involved in how an electric bell works. • This circuit is called a make and break circuit. Explain why you think it has this name. Animated Science 2020

How an Alarm Bell Works… 1. When the switch is on, the circuit is

How an Alarm Bell Works… 1. When the switch is on, the circuit is completed and current flows. 2. The electromagnet becomes magnetised and hence both ends attract the soft-iron armature and at the same time pull the hammer to strike the gong. 3. As soon as the hammer moves towards the gong, the circuit is broken. The current stops flowing and the electromagnet loses its magnetism. The field collapses. 4. This causes the spring to pull back the armature and reconnect the circuit again. 5. When the circuit is connected, the electromagnet regains its magnetism and pull the armature and hence the hammer to strike the gong again. 6. This cycle repeats and the bell rings continuously. https: //youtu. be/q. MB 5 n. Qm. B 82 M Animated Science 2020

Electromagnetic Bell – Sentence Starters As soon as the hammer moves towards the gong…….

Electromagnetic Bell – Sentence Starters As soon as the hammer moves towards the gong……. . When the circuit is connected, the electromagnet regains its magnetism …… This causes the spring to pull back the armature ……. When the switch is on……. This cycle repeats …. . The electromagnet becomes magnetised ……. Animated Science 2020

Electromagnetic Bell – Extra Help - Jumble As soon as the hammer moves towards

Electromagnetic Bell – Extra Help - Jumble As soon as the hammer moves towards the gong, the circuit is broken. The current stops flowing and the electromagnet loses its magnetism. When the circuit is connected, the electromagnet regains its magnetism and pull the armature and hence the hammer to strike the gong again. This causes the spring to pull back the armature and reconnect the circuit again. When the switch is on, the circuit is completed and current flows. This cycle repeats and the bell rings continuously. The electromagnet becomes magnetised and hence attracts the softiron armature and at the same time pull the hammer to strike the gong. Animated Science 2020

Relay switches are two electrical circuits connected by an electromagnetic switch. The smaller current

Relay switches are two electrical circuits connected by an electromagnetic switch. The smaller current activates the electromagnets to complete the larger circuits. A common feature is how a small instrument panel can turn on a larger current safely. Low Current Circuit Instrument Panel (Safe) EM Relay Switch High Current Circuit (Dangerous) Animated Science 2020

Electromagnetic Relay A relay is an electrical switch that opens and closes under the

Electromagnetic Relay A relay is an electrical switch that opens and closes under the control of another electrical circuit. 1. A relay has at least two circuits. One circuit can be used to control another circuit. 2. The 1 st circuit (input circuit) supplies current to the electromagnet. The electromagnet is magnetised and attracts one end of the iron armature. High Current Circuit (Dangerous) 3. The armature is then closes the contacts (2 nd switch) and allows current flows in the second circuit. EM Relay Switch 4. When the 1 st switch is open again, the current to the electromagnet is cut, the electromagnet loses its magnetism and the 2 nd switch is opened. Stopping the current flow. Low Current Circuit Instrument Panel (Safe) Animated Science 2020

Electromagnetic Relay – Extra Help - Jumble A relay is an electrical switch that

Electromagnetic Relay – Extra Help - Jumble A relay is an electrical switch that opens and closes under the control of another electrical circuit. The 1 st circuit (input circuit) supplies current to the electromagnet. The electromagnet is magnetised and attracts one end of the iron armature. The armature is then closes the contacts (2 nd switch) and allows current flows in the second circuit. When the 1 st switch is open again, the current to the electromagnet is cut, the electromagnet loses its magnetism and the 2 nd switch is opened. A relay has at least two circuits. One circuit can be used to control another circuit. Thus current stop to flow in the 2 nd circuit. Animated Science 2020

Electromagnetic Relay – Sentence Starters A relay is an electrical switch that opens …….

Electromagnetic Relay – Sentence Starters A relay is an electrical switch that opens ……. The 1 st circuit (input circuit) supplies current to the electromagnet. The electromagnet is magnetised and ……. The armature is then closes the contacts (2 nd switch) and allows ……. When the 1 st switch is open again, the current to the electromagnet is cut, ………. A relay has at least two circuits. ……. Thus current stop to……. Animated Science 2020

Exam Question Long Answer… Circuit breakers help to make the electricity supply in homes

Exam Question Long Answer… Circuit breakers help to make the electricity supply in homes safer. A circuit breaker is an automatic safety switch. It cuts off the current if it gets too big. Describe, in as much detail as you can, how this circuit breaker works. (6 marks) Answers… bolt out -> plunger up > switch off -> circuit broken (1 mark) -----------+ any five from • high current flows • electromagnet is stronger • the iron bolt is pulled out • the plastic plunger moves up • the switch is lifted / open / off accept circuit is broken • no current flowing • to re-set the plunger must be pushed down Animated Science 2020

Circuit Breakers (3 types) – Recap Mains Y 9 A circuit breaker acts as

Circuit Breakers (3 types) – Recap Mains Y 9 A circuit breaker acts as a safety device in a circuit similar to a reusable fuse. 1. A simple electromagnet where an increase in current causes an iron bar to pivot and break the circuit. This can be reset with a switch on a spring. 2. A bimetallic strip which bends when too much current flows due to heating causing a break. 3. A RCCB (Residual Current Circuit Breaker) which is similar to an electromagnet but faster and more sensitive as it looks at the differences between live and neutral connections. The difference in fields cause a pivot to turn, breaking the circuit. 1. What does a circuit breaker do? 2. What key Physics makes it work? 3. What is the sequence of events? Animated Science 2020

Circuit Breakers (3 types) Animated Science 2020

Circuit Breakers (3 types) Animated Science 2020

Lesson 4 Electromagnets in Action Animated Science 2020

Lesson 4 Electromagnets in Action Animated Science 2020

Lesson 4 Electromagnets – Review Questions 1) Why is an electromagnet core made of

Lesson 4 Electromagnets – Review Questions 1) Why is an electromagnet core made of iron? 2) Explain what would happen if the core was made of steel? 3) Suggest why an alarm bell is called a “make-andbreak” circuit? 4) Why does the hammer keep moving in the circuit? 5) Why is a relay so useful for a car starter motor? Answers… 1) Iron is a magnetic material and so becomes magnetised in the coil’s magnetic field. This makes the magnetic field stronger. The field passes through the iron more easily than air. 2) Once steel has been magnetised it remains permanently magnetised (Hard magnetic material). So once the electromagnet is switched on it will be permanently magnetised even when it is switched off. 3) The iron contact strip alternately makes contact and breaks contact. 4) The electromagnet attracts the iron contact strip when a current flows through it. When the hammer strikes the gong the contact is broken so no current flows. The electromagnet no longer attracts the iron contact strip and the spring moves back. 5) A dangerous and large current is kept away from the main instrument panel and driver. Animated Science 2020

Review Maths Task – Y 9 Sats Paper Challenge Task… 1. What are the

Review Maths Task – Y 9 Sats Paper Challenge Task… 1. What are the variables in this experiment. Write your ideas on a whiteboard…. OR on your sheet. 2. What can you deduce from the information on the image…. 3. Do you agree with the statement, “The strength of an electromagnet is always directly proportional to the number of turns on the coil. ” if so (OR not) why…. 4. How many turns and Amps could pickup 23 paperclips? Animated Science 2020

Plenary / Review Challenge Task… 1. What are the variables in this experiment. Write

Plenary / Review Challenge Task… 1. What are the variables in this experiment. Write your ideas on a whiteboard…. OR on your sheet. 2. What can you deduce from the information on the image…. 3. Do you agree with the statement, “The strength of an electromagnet is always directly proportional to the number of turns on the coil. ” if so (OR not) why…. 4. How many turns and Amps could pickup 23 paperclips? Animated Science 2020

Answers in full…. Clearly the more turns the more paperclips you pick up. However,

Answers in full…. Clearly the more turns the more paperclips you pick up. However, also the more current you have the more paperclips you pick up. Comparison = Number amps and turns to pickup a paperclip OR Amps x Turns / Paperclips M has 20 turns and 1 A. It picks up 6 paperclips. So…. 1 A x 6/20 = 0. 3 paperclips per turn per Amp J = 1 A x 10 turns / 3 paperclips = 3. 33 amps turns per paperclip K = 2 A x 20 turns / 12 paperclips = 3. 33 amps turns per paperclip L = 1 A x 30 turns / 9 paperclips = 3. 33 amps turns per paperclip M = 1 A x 20 turns / 6 paperclips = 3. 33 amps turns per paperclip N = 4 A x 15 turns / 18 paperclips = 3. 33 amps turns per paperclip Answer = 2 A x 39 turns / 23 paperclips = 3. 33 amps turns per paperclip ( They have to rearrange it) Animated Science 2020

Plenary / Review Challenge Task…… 1. What are the variables in this experiment. 2.

Plenary / Review Challenge Task…… 1. What are the variables in this experiment. 2. What can you deduce from the information on the image. 3. Do you agree with the statement, “The strength of an electromagnet is always directly proportional to the number of turns on the coil. ” if so (OR not) why…. 4. How many turns and Amps could pickup 23 paperclips? Write your ideas here…. .