How large is the voltage generated?

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SUMMARY

The discussion centers on calculating the electromotive force (EMF) generated by a home-built generator designed by a Boulder farmer to power a television. The farmer utilizes the Earth's magnetic field, which has a magnitude of 53 µT and an angle of 66 degrees with the horizontal. The setup includes a sliding rail of 15 meters in length, with the horses pulling it at a speed of 8 miles per hour. The correct formula for EMF is identified as EMF = B * A * cos(theta), where A is the area swept by the conductor, indicating that the initial calculations presented were incorrect.

PREREQUISITES
  • Understanding of electromotive force (EMF) and its calculation
  • Familiarity with magnetic fields and their properties
  • Knowledge of basic physics equations related to force and work
  • Ability to convert units, specifically miles per hour to meters per second
NEXT STEPS
  • Learn about the principles of electromagnetic induction
  • Study the calculation of EMF using the formula EMF = B * A * cos(theta)
  • Explore the conversion of speed units from miles per hour to meters per second
  • Investigate the relationship between magnetic field strength and voltage generation
USEFUL FOR

Students studying physics, particularly those focusing on electromagnetism, as well as hobbyists interested in building generators and understanding their operational principles.

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Homework Statement


A Boulder farmer, frustrated by his monthly electricity bill, decides to power his extra-
large-screen television set by using a home-built generator. He knows that the Earth
acts like a huge magnet and wants to make use of this magnetic field to generate an
electromotive force (voltage difference) for his TV. The generator is made up of two
large conductors coming out of the house, connected to a large sliding (conducting)
rail pulled by his two horses, as shown in the diagram on the left below. In Boulder
the angle of the Earth’s magnetic field, which is pointing into the ground, with the
horizontal (ground) is 66o (see diagram on the right below) and the magnitude of the
field is 53 µT (micro T). The TV acts effectively like a 4 Ω resistor in the circuit, and
the friction between the moving parts is negligible.
Length of the slide is 15 m and a width of 25 m.

The horses can pull the sliding rail with 8 miles per hour. How large is the
voltage generated across the leads to the TV?


Homework Equations



so it would be EMF = bcos(theta)*voltage*length

The Attempt at a Solution


well i got an answer of like .001 V and that just doesn't seem right but i don't really know, just wanted to check
 
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sorry got a little more with this. so i found the Magnetic force to be 3.03x10^-23 which again doesn't seem right. i did Fmag=q(v*B) so 1.6*10^-19(3.58x.000058T) So then i need to find the work done which would just be the Force x velocity but i got my work as something very low so again i just don't know if that makes sense.
 
shimizua said:

Homework Equations



so it would be EMF = bcos(theta)*voltage*length

That doesn't look right. The correct formula for EMF involves area ...
 

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