Tuesday, January 4, 2011

Topic 12 Homework 04/01/2011

Syllabus Statements: 12.1.1 to 12.1.5

12.1.1 Describe the inducing of an emf by relative motion between a conductor and a magnetic field.

A conductor is full of free electrons. When it is moved through a magnetic field, a magnetic Force b (that can be found using Flemmings Left Hand rule) acts on the electrons and pushes the electrons to one side of the conductor. This creates a side with a negative charge and another side with a positive charge and thus creates a potential difference between the ends of the conductor. Due to this potential difference, an emf is induced. Force e acts equal but opposite to Force b and therefore the electrons stay in place (stop moving).

12.1.2 Derive the formula for the emf induced in a straight conductor moving in a magnetic field.


12.1.3 Define magnetic flux and magnetic flux linkage.
Magnetic flux: The product of magnetic field strength and a perpendicular area.
Magnetic flux linkage: The product of the no. of turns of a coil and magnetic flux.

12.1.4 Describe the production of an induced emf by a time-changing magnetic flux.

Changing the direction of the magnetic field has the same effect as moving the conductor in 12.1.1. As the magnetic field changes direction, it changes the direction of the force on the electrons and thus gives rise to an induced current.

12.1.5 State Faraday’s law and Lenz’s law.

Faraday's law: The induced emf is equal to the rate of change of flux.
Lenz's law: The direction of the induced current is such that it will oppose the change producing it.


Homework Questions
Pages 211 & 213

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