Converting mechanical to electrical energy

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SUMMARY

The discussion centers on the conversion of mechanical energy to electrical energy using a hand-cranked generator. When the bulb is turned on, the crank becomes harder to turn due to the back electromotive force (back EMF) generated by the current flowing through the circuit. This back EMF opposes the motion of the crank, requiring more effort from the user. The energy required to light the bulb is supplied by the mechanical work done by the person operating the crank.

PREREQUISITES
  • Understanding of basic electrical concepts, including voltage and current.
  • Familiarity with electromagnetic principles, particularly back EMF.
  • Knowledge of mechanical energy conversion processes.
  • Basic grasp of circuit components, such as switches and bulbs.
NEXT STEPS
  • Research the principles of back electromotive force (back EMF) in electrical circuits.
  • Explore the workings of hand-cranked generators and their applications.
  • Study the relationship between mechanical work and electrical energy conversion.
  • Investigate the role of magnetic fields in generating electricity.
USEFUL FOR

Students in physics, electrical engineers, educators demonstrating energy conversion, and anyone interested in the fundamentals of electricity generation.

MrLobster
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I was watching an experiment that I don't understand. The professor turned a hand crank that generated electricity to light up a bulb. There was also a switch to turn the bulb on and off. When the bulb was on the crank became harder to turn. I don't really understand why that is. Did it somehow create a magnetic force that opposed the motion of the crank?
 
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MrLobster said:
I was watching an experiment that I don't understand. The professor turned a hand crank that generated electricity to light up a bulb. There was also a switch to turn the bulb on and off. When the bulb was on the crank became harder to turn. I don't really understand why that is. Did it somehow create a magnetic force that opposed the motion of the crank?
The current created by the changing magnetic force also creates an opposing EMF to the magnetic which created the current.
 
Another way to look at it is this - the energy that lights the bulb is being provided by the person turning the crank. If the bulb is off, you have to do less work and the handle turns easily. When the light is on it feels harder because you're working against the back emf created by the flowing current, as Astronuc has said above.
 

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