Chapter 22 Electric Fields Flashcards
Define electric field strength at a point in space
Force per unit positive charge
Magnetic flux linkage
magnetic flux x number of turns
The flux linking through a coil
Faraday’s law
The magnitude of the induced EMF is directly proportional to the rate of change of magnetic flux linkage
Lenz’s law
The direction of an induced EMF or current is always such as to oppose the change producing it.
Similarity and difference between electric field of a point charge and gravitational field of a point mass.
Similarity = Force is inversely proportional to the square of the distance between the objects.
Difference = The type of field produced is always attractive in a gravitational field and can be repulsive in an electric field.
Two protons fuse together, why are the protons able to remain together?
strong attractive nuclear force
How is an EMF induced in the secondary coil in a transformer?
A changing flux is produced and the iron core links the flux to the second coil, the change in flux linkage induces an EMF
What is Coulombs law?
Any two point charges exert an electrostatic force on each other that is directly proportional to the square of the distance between them.
What is electric potential energy?
Stored energy in a charged particle
The energy required to move a positive charged particle from infinity to a distance from another like charged object.
What is the use of an iron core in a transformer?
It stops eddie currents and facilitates a low resistance path for the magnetic flux linkage between the primary and secondary coils
What is magnetic flux linkage?
The product of the number of turns in a magnetic field and the magnetic flux.
Describe a simple ac generator?
An AC generator is an electromagnetic device which turns mechanical energy into electrical energy. A current carrying wire cuts an electromagnetic field inducing an EMF which is constantly oscillating between positive and negative values.
