Unit 4.5 - Electromagnetic Induction Flashcards
Induction
Cause something to happen
What is electromagnetic indication?
The phenomenon that electricity could be generated by moving a magnetic material relative to a conductor
What is used to generate electricity via electromagnetic induction?
Magnetic fields
Magnetic field strength (B)
This is a vector quantity. Its direction is that in which the North Pole of a freely-pivoted magnet points. Its magnitude is defined by B = F/Il, in which F is the force on a length l of a wire carrying a current I, placed perpendicular to the direction of the field. Unit T.
What is the model we can use to imagine a magnetic field?
A flow model
Magnetic flux unit
Wb
Magnetic flux symbol
φ
What is magnetic flux?
It described the “flow” of magnetism around a magnet or a wire carrying a current
What is the way we consider magnetic flux similar to?
The way we consider a flow of light from a lamp
How would we determine the intensity of a light source at a distance from it with a lamp?
By measuring the rate at which light energy passes through a given area and dividing this rate with the area
How do we get flux density?
Imagine an area A with a uniform magnetic field B passing through it
The total magnetic flux density passing through the area divided by the area gives us the flux density B at this point
How can we visually imagine flux density?
Judge how closely bunched up the lines of the field are
Flux density symbol
B
What is flux density, B?
The flux per m^2
Flux density (B) equation
B = φ/A
What is the total flux equation and how do we get to this?
φ = ABcostheta
B = φ/A
If this area is at an angle theta to the field then the formula is modified to only involve the perpendicular component of the flux density and becomes:
B = φ/Acostheta
Which is rearrange to calculate the total flux into the top equation
What does each turn in a coil have flowing through it?
A magnetic flux φ
Flux linkage
The total magnetic flux through a circuit
The total magnetic flux through a circuit
Flux linkage
Flux linkage symbol
N φ
N φ
Flux linkage
Flux linkage equation to learn
φ = BANcostheta
φ = BANcostheta
What does this equation calculate?
Flux linkage
What appends in a circuit if the flux linkage through the ciruit changes?
An emf is induced