What is a Magnetic Circuit?
The closed path through which magnetic flux flows; analogous to an electrical circuit where current flows.
What is Magnetic Flux (Φ)?
The total magnetic field passing through an area; measured in webers (Wb).
What is Flux Density (B)?
Magnetic flux per unit area (B = Φ/A); measured in teslas (T).
What is Magnetomotive Force (MMF)?
The magnetic ‘driving force’ that pushes flux through a magnetic circuit (MMF = N·I).
What is Reluctance (ℜ)?
Opposition to magnetic flux in a circuit; depends on path length, area, and material permeability.
What does Ampere’s Law state?
States that the magnetic field intensity around a closed path is proportional to the current through it (H·dl = NI).
What is Magnetic Ohm’s Law?
The relationship between flux, MMF, and reluctance (Φ = MMF / ℜ).
What is a Transformer?
A device that transfers electrical energy between circuits through electromagnetic induction.
What does Faraday’s Law of Induction state?
A voltage is induced in a coil when the magnetic flux linking it changes with time (e = −N·dΦ/dt).
What is Ampere’s Law in transformers?
The magnetizing force in the core depends on current and turns (NpIp = NsIs in ideal conditions).
What is the Turns Ratio?
The ratio of primary to secondary turns in a transformer (Np/Ns), which determines voltage ratio (Vp/Vs = Np/Ns).
What is an Ideal Transformer?
A lossless transformer where input power equals output power (VpIp = VsIs).
What is a Referred Circuit?
A simplified transformer circuit where all impedances are expressed on one side using the turns ratio squared.
What is a DC Motor?
A device that converts electrical energy into mechanical rotation using direct current.
What is an Armature?
The rotating part of a DC motor where current flows and torque is produced.
What is Field Winding?
Stationary coils that create the magnetic field for the armature to interact with.
What is a Commutator?
A mechanical switch that reverses current direction in the armature to maintain torque direction.
What is the Lorentz Force?
The force on a current-carrying conductor in a magnetic field (F = BIL), which produces motion in a motor.
What is Back EMF (E₍b₎)?
The induced voltage that opposes the supply voltage as the motor spins, regulating current.
What is Torque (T)?
The rotational force produced by a motor; proportional to flux and armature current (T = kₜΦIₐ).
What is the Voltage Equation?
The balance of applied voltage, back EMF, and internal resistance (V = E₍b₎ + IₐRₐ).
What is an AC Machine?
A motor or generator operating on alternating current to produce a rotating magnetic field.
What is a Synchronous Motor?
A motor whose rotor locks in with the rotating magnetic field and spins at synchronous speed.
What is an Induction Motor?
A motor where the rotor current is induced by the stator’s rotating magnetic field; runs slightly below synchronous speed.
