Electromagnetic Induction Flashcards
What is magnetic flux?
Magnetic flux is the product of magnetic flux density perpendicular to an area
What is the equation for magnetic flux?
Φ = BAcosθ
θ is the angle between the field lines and the normal.
What is magnetic flux linkage?
Magnetic flux linkage is the product of magnetic flux density going through a coil
What is the equation for magnetic flux linkage?
NΦ = NBAcosθ
N is the number of coils
What is Faraday’s Law of induction?
The induced EMF is directly proportional to the rate of change of magnetic flux linkage.
What is Lenz’s law?
The direction of the induced current is so as to oppose the change producing it.
What is the equation for an Induced EMF?
E = -(NΦ/t)
How can you generate an induced EMF?
Change the magnetic flux density of the field
Increase the area of the coil in the field or rotate the coil
Move the coil relative to the field
What is Fleming’s right hand rule used for?
To identify the direction of the induced current
What is Fleming’s right hand rule?
Thumb = Direction of the thrust of force
First Finger = Direction of the magnetic field
Middle finger = Direction of the current
What is the alternative method of finding EMF using faraday’s law?
By considering the moving conductor as a cell, the electrons within the conductor will experience a force as they move through the magnetic field and by using FLHR the direction of the force is obtained
The work done on the electrons is that force multiplied by the distance
WD = Bqv * L
However as we are taking the moving conductor to be a cell then the WD is also equal to
WD = E * q
And by equating both and making EMF (E) the subject You obtain the equation:
BLv = E
How do generators work?
Generators use rotating coils within a magnetic field to induce an emf
What factors affect the emf of a generator?
Flux Density
Area of coil
Angular velocity of rotation
