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AC Generator

Extracts from this document...

Introduction

AIM

Research, design and build an electric AC generator. Control and record the effects of changing two variables (varying the space between the magnets and the armature, the velocity of relative motion between the coil and the magnets).

HYPOTHESIS

  • As we spin the coil relative to the magnets, the coils should created an electric current that lights up our light bulb or makes movement on the galvanometer.
  • The more coils we add, the greater the current produced when in action.
  • The closer the magnets relative to the armature, the greater the magnetic field on the armature and the greater the current produced when in action.
  • The faster the velocity of relative motion between the coil and the magnets, the greater the current produced.

EQUIPMENT

  • 2 Magnets (to produce a magnetic field in the coils)
  • Insulated copper wire (for the current to flow through)
  • Wood block (for the base)
  • Metal axel (for the armature to spin on)
  • Wood core (cylinder shape to act as the armature)
  • 2 thin metal rectangular pieces (act as the brushes)
  • 2 metal slip rings (to connect to the brushes)
  • Light Bulb (test if its producing current)
  • Tape and glue (stick stuff together)
  • 2 small wood pieces (to support the axel at either end)
  • Electric hand drill (spin the generator)
  • Galvanometer (test the current)

METHOD

...read more.

Middle

RESULTS

milli Volts (mV)

 Speed

Trial 1

 Trial 2

 Trial 3

 Trial 4

 Average

 Slow

10

12

13

11

11.5

 Medium

15

20

18

20

18.25

 Fast

31

34

35

33

33.25

image01.jpg

CONCLUSION

The hypothesis stated:

  • As we spin the coil relative to the magnets, the coils should created an electric current that lights up our light bulb or makes movement on the galvanometer.
  • The faster the velocity of relative motion between the coil and the magnets, the greater the current produced.

As we spined the axle, spinning the coil on the armature relative to the magnets, the coils created an electric current that gave readings on the galvanometer. From our results we can conclude that the faster the velocity of relative motion between the coil and the magnets, the greater the current produced. Therefore our results support the hypothesis stated earlier and the hypothesis was true.

MY EXPECTED RESULTS

  • As we spin the coil relative to the magnets, the coils should created an electric current that lights up our light bulb or makes movement on the galvanometer.
  • The faster the velocity of relative motion between the coil and the magnets, the greater the current produced.

RESEARCHED RESULTS

My researched results were very similar to my expected results, only they were more accurate then mine since the way I tested my variables weren’t that precise.

...read more.

Conclusion

the roles of the rotor and the stator can be reversed for the output currentbrushes do not wear as fast as in a DC generatorno possibility of creating an electrical short circuit between segments in an alternator because the slip rings are already continuousmost commercial generators are AC generatorsbetter suited to high current demands
  • more deadly than DC
  • has losses through electromagnetic radiation or magnetic induction.
  • Back emf opposes supplied emf.
  • Emits EMR, so wires need insulation and shielding.
  • Frequency must be sent to consumers at 50Hz. This has to be maintained and monitored.
  • AC has a “skin-effect”; the electrons tend to travel at the edge of the conductor, which makes them slightly less efficient.

DC GENERATORS

Advantages

Disadvantages

  • output can be made smoother by the arranging many coils in a regular pattern around the armature
  • use with equipment that needs a steady voltage rather than varying voltage (AC)
  • doesn’t cause losses through electromagnetic radiation or magnetic induction.
  • not good for transmission over long distances without great energy losses
  • more complicated to make and maintain
  • limited usefulness of DC generators to relatively low current applications
  • large currents through the commutator-brush connection increases the likelihood of electric arcs forming as the brush breaks contact with each bar in turn

REFERENCES

Author : Ken J Williams and Janet Pembertonimage02.png

Publisher : Science Press

Published : 2002

Book : Spotlight Physics HSC

  • Jacaranda HSC Physics
  • Spotlight HSC Physics
  • http://www.phys.unsw.edu.au/~jw/HSCmotors.html
  • http://www.amasci.com/amateur/coilgen.html

...read more.

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