Magnetism
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This text is meant to accompany class discussions. It is not everything there is to know about uniform circular motion. It is meant as a  prep for class. More detailed notes and examples are given in the class notes, presentations, and demonstrations. See the links below.
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Ohm's Law Review

This content is important and will be use when problem solving.

Faraday's law

 

By rapidly change the magnetic flux inside of closed shape made from a conductor, an emf is induced. In other words, when you poke a magnet in and out of hoop made from a conductor, like metal, a potential difference is created between the ends of the metal.

Below is the equation associated with Faraday's law.

Faraday's Law Equation

  • εinduced : Potential difference between the two ends of the wire that makes a wrapped coil. It is measured in volts, [v.]
  • N: The number of coils
  • ΦB : Magnetic flux measured in Webers [Wb.] A Weber is equal toT•m2.
  • Δt : The change in time measured in seconds [s]
 
Example
  • Question
  • Solution
A coil of wire has 110 loops of insulating wire. The flux inside of the coil changes from 0.500 Wb to 3.50 Wb in 0.100 seconds. If the resistance of the coil 2000 Ohms, then how much current is generated?

A coil of wire has 110 loops of insulating wire. The flux inside of the coil changes from 0.500 Wb to 3.50 Wb in 0.100 seconds. If the resistance of the coil 2000 Ohms, then how much current is generated?

There are several ways to find current. The potential difference is directly proportional to the change in flux. This can be used to find the current because the potential difference is directly proportional to the current from Ohm's law.

 
Example

A coil changes shape while in a uniform magnetic field of 100T from 0.50 m2 to 0.1 m2 in 0.050 seconds. What is the direction of the generated current and what is the magnitude of the emf?

 
Example 3

A coil changes orientation as shown while in a uniform magnetic field of 10T in 0.010 seconds. What is the magnitude of the emf? If the coil has a resitance of 5.0 Ohms, then what is the magnitude of the generated current?

 
4 Examples from a graph

This video can be found on YouTube at https://youtu.be/-psuHYHOAdo

 
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by Tony Wayne ...(If you are a teacher, please feel free to use these resources in your teaching.)