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Electromagnetism

Electromagnetism. The Motor Effect 29/08/2014. Aim: To use Flemming’s Left Hand Rule To explain how a motor works To construct a motor. Fields Bar Magnets. Single Science Only. handout. Opposite Poles. Single Science Only. Same Poles. Single Science Only. Fields due to Current.

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Electromagnetism

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  1. Electromagnetism

  2. The Motor Effect29/08/2014 • Aim: • To use Flemming’s Left Hand Rule • To explain how a motor works • To construct a motor

  3. Fields Bar Magnets Single Science Only handout

  4. Opposite Poles Single Science Only

  5. Same Poles Single Science Only

  6. Fields due to Current

  7. Single Science Only Single Coil of Wire Solenoid

  8. Magnetic Field Lines There are magnetic field lines around every Magnet Electrical wire (with current flowing through it) Anything magnetic in the field will experience a force

  9. Wire in a magnetic field

  10. The Catapult (Motor) Effect

  11. Motor Effect If a conductor carrying an electric current moves through magnetic field lines at right angles it will experience a force. A charged particle will experience the same effect

  12. Fleming's left hand rule

  13. Increasing the Size of the Force

  14. The motor effect: true or false?

  15. Coil in a Magnetic Field

  16. How does an electric motor work?

  17. DC electric motor simulation

  18. How do we increase motor strength? Would the same strength motor be used in both of these? How can the strength of an electric motor be increased? • increase the current flowing through the coil • increase the strength of the magnet • increase the number of turns on the coil Worksheet

  19. The Motor Effectrecap

  20. Induction29/08/2014 • Aim: • To observe and define induction • To explain how electricity is generated

  21. Inducing current in a wire

  22. What is electromagnetic induction? Current Carrying Wire + Magnetic field = Motion Motion + Magnetic field = Current in Wire Changing Magnetic field = Current in wire If they are at right angles to each other

  23. Inducing current in a coil

  24. Induction • If a magnet is moved near a coil of wire a current is induced in the wire • Faster motion, bigger current • Stronger magnet, bigger current • More turns, bigger current • Change direction of motion, change direction of current

  25. Factors affecting induced current

  26. How can motion produce a current?

  27. What are 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 • wind – in wind turbines • falling water – in hydroelectric power stations

  28. How do AC generators work?

  29. AC generator simulation

  30. Induction: true or false?

  31. What is a transformer? The voltage of an alternating current can be changed using a device called a transformer. iron core A transformer contains two coils that are wound around a soft iron core. The alternating current in the primary (input) coil produces an alternating magnetic field. This alternating magnetic field induces an alternating current in the secondary (output) coil. secondary coil primary coil

  32. How does a transformer change voltage? The voltage induced in the secondary (output) coil depends on the number of turns on the primary and secondary coils. A step-up transformer has more turns on the secondary coil and so increases voltage. A step-down transformer has fewer turns on the secondary coil and so decreases voltage.

  33. How are transformers used to supply electricity?

  34. Transformers • Transformers are used to change the voltage from the Primary (input) to the Secondary (output) • They only work with a.c. (alternating current) • Input (Primary) Voltage = Number of Primary Turns Output (secondary) Voltage Number of Secondary Turns • Example Question: • Input voltage = 230 V • Primary turns = 10000 • Secondary turns = 500 • What is the secondary voltage? Worksheet

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  36. USE ME IN THIS PRESENTATION

  37. http://intranet.stthomasmore.org.uk/resource/Absorb%20Physics/Absorb%20Physics%20for%20A-level/Absorb%20Physics%20for%20A-level/HTML/units/080300.htmlhttp://intranet.stthomasmore.org.uk/resource/Absorb%20Physics/Absorb%20Physics%20for%20A-level/Absorb%20Physics%20for%20A-level/HTML/units/080300.html

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