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Boardworks GCSE Additional Science: Physics Motors and Generators

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Presentation on theme: "Boardworks GCSE Additional Science: Physics Motors and Generators"— Presentation transcript:

1 Boardworks GCSE Additional Science: Physics Motors and Generators

2 Boardworks GCSE Additional Science: Physics Motors and Generators

3 Electromagnetism and movement
Boardworks GCSE Additional Science: Physics Motors and Generators What is the link between movement, magnetism and electric current? Teacher notes This illustration contains several discussion points about the relationship between movement, magnetism and electric current, for example: The Hamster Power and DYNaMoWeR stands introduce the idea that rotational movement can result in the production of electric current, and suggest more unusual means of powering a generator. The handheld fan powered by a wind turbine highlights the link between motors and generators. Students could be asked to explain some of the more bizarre – and scientifically-dubious – inventions on display! The more eagle-eyed observers may notice that the girl in charge of the Hamster Power stand is the same girl from the illustration in the Boardworks GCSE Science (Physics) ‘Electricity to the Home’ presentation. After receiving a mammoth electricity bill due to her love of electrical gadgets, she decided to do her bit for the green movement and pioneer an environmentally-friendly source of electricity. However, the RSPCA have yet to be informed of her activities.

4 Wire in a magnetic field
Boardworks GCSE Additional Science: Physics Motors and Generators Teacher notes This virtual experiment can be used as an introduction to the motor effect or as a revision exercise.

5 Changing the direction of the force
Boardworks GCSE Additional Science: Physics Motors and Generators The direction of the force acting on a wire in an electromagnetic field can be reversed by: reversing the current reversing the magnetic field The direction of the force is therefore relative to both the direction of the magnetic field and the current.

6 Fleming’s left-hand rule
Boardworks GCSE Additional Science: Physics Motors and Generators It is possible to predict the direction of the force acting on a wire – its motion – if the direction of the current or the magnetic field are known. Fleming’s left-hand rule is used to do this. thuMb = Motion First finger = magnetic Field Teacher notes Students should be made aware that the direction of a magnetic field is usually taken as being N-S rather than S-N, and the direction of current is the direction of conventional current, i.e. positive to negative. seCond finger = Current

7 Increasing the size of the force
Boardworks GCSE Additional Science: Physics Motors and Generators

8 Coil in a magnetic field
Boardworks GCSE Additional Science: Physics Motors and Generators Teacher notes This activity extends the idea of a current-carrying wire in a magnetic field from slide 4, and introduces the concept of current-carrying coil experiencing rotational force. Students could be asked to interpret the movement of the coil using Fleming’s left-hand rule, and begin to think about how an electric motor works.

9 The motor effect: true or false?
Boardworks GCSE Additional Science: Physics Motors and Generators Teacher notes This true-or-false activity could be used as a plenary or revision exercise on the motor effect, or at the start of the lesson to gauge students’ existing knowledge of the subject matter. Coloured traffic light cards (red = false, yellow = don’t know, green = true) could be used to make this a whole-class exercise.

10 Boardworks GCSE Additional Science: Physics Motors and Generators

11 What are electric motors?
Boardworks GCSE Additional Science: Physics Motors and Generators How many items do you own that contain an electric motor? An electric motor is a device that converts electrical energy into mechanical energy to produce a turning effect. Most motors are powered using direct current (DC), which is produced by cells and batteries. Photo credit: © 2007 Jupiterimages Corporation Motors powered by mains electricity use alternating current (AC). These motors use electromagnets rather than permanent magnets.

12 How does an electric motor work?
Boardworks GCSE Additional Science: Physics Motors and Generators Teacher notes This activity extends the idea of a simple current-carrying coil rotating in magnetic field from slide 8, and explains how a split-ring commutator enables a coil to continue rotating. Students could again be asked to interpret the movement of the coil using Fleming’s left-hand rule.

13 DC electric motor simulation
Boardworks GCSE Additional Science: Physics Motors and Generators Teacher notes This simulation takes the concepts from the previous slide to create an animated motor simulation. The current, forces and magnetic field can be toggled on and off, to aid visualization and understanding, and the speed and direction of rotation can be altered.

14 How do we increase motor strength?
Boardworks GCSE Additional Science: Physics Motors and Generators Would the same strength motor be used in both of these? How can the strength of an electric motor be increased? Photo credits: © 2007 Jupiterimages Corporation increase the current flowing through the coil increase the strength of the magnet increase the number of turns on the coil

15 Boardworks GCSE Additional Science: Physics Motors and Generators

16 Inducing current in a wire
Boardworks GCSE Additional Science: Physics Motors and Generators Teacher notes This virtual experiment can be used as an introduction to electromagnetic induction or as a revision exercise.

17 Fleming’s right-hand rule
Boardworks GCSE Additional Science: Physics Motors and Generators It is possible to predict the direction of the induced current produced by a generator if the direction of the force (or motion) or the magnetic field are known. Fleming’s right-hand rule is used to do this. thuMb = Motion First finger = magnetic Field Teacher notes Students should be made aware that the direction of a magnetic field is usually taken as being N-S rather than S-N, and the direction of current is the direction of conventional current, i.e. positive to negative. seCond finger = Current

18 What is electromagnetic induction?
Boardworks GCSE Additional Science: Physics Motors and Generators When current flows through a wire held in a magnetic field, a force is created that moves the wire. The opposite is also possible: if a wire is moved across a magnetic field, a current is produced. This is called electromagnetic induction. Induction also occurs if a magnet is moved in a coil of wire, or if a coil of wire rotates in a magnetic field. In all these methods of inducing a current, the wire and magnetic field move perpendicular to each other. If they move parallel to each other, no current is induced.

19 Inducing current in a coil
Boardworks GCSE Additional Science: Physics Motors and Generators Teacher notes This virtual experiment can be used as an alternative introduction to electromagnetic induction or as a revision exercise.

20 Boardworks GCSE Additional Science: Physics Motors and Generators
What are generators? Boardworks GCSE Additional Science: Physics Motors and Generators A generator is a device that converts mechanical energy into electrical energy. It is the opposite of an electric motor. Power stations use generators to produce electricity on a large scale. Mechanical energy is provided by rotating turbines that can be powered by: high-pressure steam – in coal, oil, gas and nuclear power stations Photo credit: Clipper Windpower / National Renewable Energy Laboratory wind – in wind turbines falling water – in hydroelectric power stations

21 How do AC generators work?
Boardworks GCSE Additional Science: Physics Motors and Generators Teacher notes This activity extends the idea of simple electromagnetic induction from slides 16 and 19, and explains how slip rings enable a generator to produce alternating current.

22 AC generator simulation
Boardworks GCSE Additional Science: Physics Motors and Generators Teacher notes This simulation takes the concepts from the previous slide to create an animated generator simulation. The current, forces and magnetic field can be toggled on and off to aid visualization and understanding.

23 Increasing the size of the induced current
Boardworks GCSE Additional Science: Physics Motors and Generators How can the size of an induced current be increased? increase the speed at which the coil rotates increase the strength of the magnetic field increase the number of turns in the coil increase the total area of the coil. In a power station generator, an electromagnet is often used as this can provide a stronger magnetic field than is possible with a permanent magnet. Photo credit: David Parsons / National Renewable Energy Laboratory The generator of Niagara Mohawk’s Dunkirk steam station in New York. This coal-fired power plant produces 600,000 kilowatts of 60 cycle power.

24 Factors affecting induced current
Boardworks GCSE Additional Science: Physics Motors and Generators Teacher notes Appropriately coloured voting cards could be used with this classification activity to increase class participation.

25 Induction: true or false?
Boardworks GCSE Additional Science: Physics Motors and Generators Teacher notes This true-or-false activity could be used as a plenary or revision exercise on electromagnetic induction, or at the start of the lesson to gauge students’ existing knowledge of the subject matter. Coloured traffic light cards (red = false, yellow = don’t know, green = true) could be used to make this a whole-class exercise.

26 Boardworks GCSE Additional Science: Physics Motors and Generators

27 Boardworks GCSE Additional Science: Physics Motors and Generators
Glossary Boardworks GCSE Additional Science: Physics Motors and Generators alternating current – A current that constantly changes direction. It is produced by most electrical generators. commutator – The part of a motor that enables the coil to rotate using direct current. direct current – A current that always flows in the same direction. It is produced by cells and batteries. generator – A device that converts mechanical energy into electrical energy. induction – Generating a current in a wire by moving the wire in a magnetic field, or by moving a magnet inside a coil. motor – A device that converts electrical energy into mechanical energy. slip rings – The parts of a generator that enable the rotating coil to produce alternating current.

28 Boardworks GCSE Additional Science: Physics Motors and Generators
Anagrams Boardworks GCSE Additional Science: Physics Motors and Generators

29 Boardworks GCSE Additional Science: Physics Motors and Generators
Multiple-choice quiz Boardworks GCSE Additional Science: Physics Motors and Generators Teacher notes This multiple-choice quiz could be used as a plenary activity to assess students’ understanding of motors and generators. The questions can be skipped through without answering by clicking “next”. Students could be asked to complete the questions in their books and the activity could be concluded by the completion on the IWB.


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