Electromagnetic Induction
Define 'Magnetic Flux'
The product of the magnetic flux density normal to the surface & area of the surface
What is 1 Weber
The Magnetic Flux through a surface if a magnetic field of flux density 1T exists perpendicularly to an area of 1m²
What does magnetic flux refer to
The no of field lines
Give the 2 equations for magnetic flux
Φ = BA
Φ = BACosθ
Φ = Magnetic Flux
B = Magnetic Flux density
A = Area of the surface
Cosθ = The angle the field lines are to the normal of the surface
Define 'Magnetic Flux Linkage'
The product of the number of turns & the magnetic flux
Give 2 formulae for 'Magnetic Flux Linkage'
NΦ
BANCosθ
N = No of turns
A = Area of coil
State Faraday's Law
The magnitude of an induced emf(or current) is proportional to the rate of change of magnetic flux linkage
State Lenz Law
The direction of induced current is always such to oppose the change that causes current
Why must the induced current create a field that opposes the motion of the incoming magnet
To stop the magnet from being sucked in faster and faster
Give the formula for Induced EMF
ε = -N × (ΔΦ/Δt)
When do you get the max EMF of a coil
When you have a minimum flux linkage (zero)
When do you get the min EMF of a coil
When you have a maximum flux linkage