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Module 6: ElectroMagnetism - Coggle Diagram
Module 6: ElectroMagnetism
IQ1: Charged Particles, Conductor & Fields
Formulas
E= V/d
Parallel Plates
Towards North Pole/Negative
F=ma= qE
W=qV =qEd
F=qvBsinO
Force on a charged particle by a magnetic field
O = angle between v and B to perpindicular
Purely formula based but may ask about direction of movement
IQ2: Motor Effect
Formulas
F=LIBsinO
L= length of conductor
I = current
B= Magnetic field strength/Magnetic Flux Density
O is angle between current and Magnetic field to perpindicular
F/L=μo/2π x I1I2/r
Analysis of force between two current carrying wires
used to define an ampere
Concept & Understanding
Set up of a simple motor
North magnet then axle then South magnet
Current inwards then current out
Force up on left down on right
Magnetic field inwards as it is loop
Additions to motor
DC
Split ring commutator that allows for change in direction of current every half spin
Brushes detect breaking and reconnecting of armature
AC
Slip Ring Commutator that adjust to change in current
emf diffirences
DC emf always positive as it returns to 0 and goes back to positive during the broken contact with the split ring
AC is changing between positive and negative as it does not break contact with slip ring and thus creates a negative emf that still allows for the motor to operate.
Both start with an initial push to the armature
The armature creates change in Φ
creating an induced emf
that then pushes opposite of intial push and starts motor
IQ4: Application of the motor effect
Formula
T=nIABsinO
O is angle between area and magnetic field to perpindicular
n is number of coils
Concepts and Understanding
Torque
Torque is the twist of Force
Proportional to SinO
as A changes angle to Force its changes torque value
Back Emf
emf that is not opposes intended emf
DC motors
when operating change in magnetic flux is experienced in coils and thus current induced and emf that is opposite to direction of original current
Back Emf is used in magnetic braking to oppose rotation of wheels
Conservation of Energy
A current must flow opposite to original change in current of magnetic flux so to keep in conservation of energy
if not, it would create a positive feedback loop
IQ3: Electromagnetic Induction
Formulas
ϵ= -N x /\Φ/t
Faradays Law is entire thing Lenz law is negative
Φ =BAcosO
Φ = magnetic flux (Wb) magnetic field lines
Vp/Vs=Np/Ns
Step or Step down transformers
VpIp=VsIs
Power loss of ideal transformers
Concepts & Understanding
Induction Motor Setup
Squirrel cage of conductor rods
Placed into stator holding with electromagnets set with AC 3 phase power to continue motion
A change in Magnetic flux or current then induces a change in the other which induces emf because F=LIB
(Ideal) Transformer Setups
Goal of transformers to convert AC Power up or down in voltage
Restrictions to efficency
Eddy currents
small current created in the electron orbits of atoms that reduce energy efficiency through heat dissipation
can be mitigated through laminated iron core that prevents creation of larger eddy currents
Incomplete flux linkage
Not 100% of magnetic field lines from primary cut through secondary
can be mitigated by reducing distance between circuits
Irons core increases the magnetic field strength of the Primary circuit via induction yap
Which then acts on the secondary circuit
Since primary is AC induces current and thus emf aka Voltage
Example
High Voltage transmission lines
Power loss = IV = I^2 R
By stepping up Voltage massively its reduce current greatly and thus less power loss
Vp/Vs=Is/Ip
Vp is inversely proportional to Is