Difference between Electromagnet and Permanent Magnet

 

Basis for Comparison	Electromagnet	Permanent Magnet
Generation of the magnetic field	Due to electric current	Due to material characteristics when magnetized.
Strength of magnetic field	The strength of the field depends on the total current flowing through the solenoid or coil.	Here the magnetic field strength solely relies on the respective material.
Magnetization	Temporary	Permanent
Type of material used	Generally the soft iron core	Usually, it makes use of hard material.
Demagnetization	It is demagnetized when the flow of current is stopped.	The material is demagnetized when it is subjected to extremely high temperatures.
The requirement of external power	Exist	Not Exist
Magnetic field retention	The field is retained till the time current flows through the material	These materials retain the field all the time.
Cost	Low	Comparatively high
Poles of the magnet	Can be varied.	Here the poles can never be changed.
Example	A solenoid across an iron	Bar Magnet
Applications	Electric bells, loudspeakers, motors, etc.	Cell phones, headphones, sensors, etc.

Difference between MAGNETIC CIRCUIT and ELECTRIC CIRCUIT

 

BASIS	MAGNETIC CIRCUIT	ELECTRIC CIRCUIT
Definition	The closed path for magnetic flux is called a magnetic circuit.	The closed path for electric current is called an electric circuit.
Relation Between Flux and Current	Flux = MMF/reluctance	Current = emf/ resistance
Units	Flux φ is measured in weber (wb)	Current I is measured in amperes
MMF and EMF	Magnetomotive force is the driving force and is measured in Ampere turns (AT) Mmf =ʃ H.dl	Electromotive force is the driving force and measured in volts (V) Emf = ʃ E.dl
Reluctance and Resistance	Reluctance opposes the flow of magnetic flux S = l/aµ and measured in (AT/wb)	Resistance opposes the flow of current R = ρ. l/a and measured in (Ώ)
The relation between Permeance and Conduction	Permeance = 1/reluctance	Conduction = 1/ resistance
Analogy	Permeability	Conductivity
Analogy	Reluctivity	Resistivity
Density	Flux density B = φ/a (wb/m2)	Current density J = I/a (A/m2)
Intensity	Magnetic intensity H = NI/l	Electric density E = V/d
Drops	Mmf drop = φS	Voltage drop = IR
Flux and Electrons	In a magnetic circuit, molecular poles are aligned. The flux does not flow but sets up in the magnetic circuit.	In electric circuit electric current flows in the form of electrons.
Examples	For magnetic flux, there is no perfect insulator. It can set up even in non-magnetic materials like air, rubber, glass, etc.	For electric circuits, there are a large number of perfect insulators like glass, air, rubber, PVC, and synthetic resin which do not allow it to flow through them.
Variation of Reluctance and Resistance	The reluctance (S) of a magnetic circuit is not constant rather it varies with the value of B.	The resistance (R) of an electric circuit is almost constant as its value depends upon the value of ρ. The value of ρ and R can change slightly if the change in temperature takes place
The energy in the circuit	Once the magnetic flux sets up in a magnetic circuit, no energy is expanded. Only a small amount of energy is required at the initial stage to creating flux in the circuit.	Energy is expanding continuously, as long as the current flows through the electrical circuit. This energy is dissipated in the form of heat.
Applicable Laws	Kirchhoff flux and MMF law is followed	Kirchhoff voltage and the current law is followed. (KVL and KCL)
Magnetic and Electric lines	Magnetic lines of flux start from the North pole and end at the South pole.	Electric lines or current starts from a positive charge and ends on a negative charge.

Difference between AC Voltage and DC Voltage

 

Basis for Comparison	AC Voltage	DC Voltage
Definition	The AC voltage is the force that derives the alternating current between the two points.	The DC Voltage induces the direct current between the two points.
Symbolic Representation
Frequency	Depends on the country.	Zero
Power Factor	Lies between 0 to 1.	0
Polarity	Changes	Remain Constant
Direction	Vary	Remain the same
Obtained From	Generator	Cell or Battery
Efficiency	High	Low
Passive Parameter	Impedance	Resistance
Amplitude	Have	Don't Have
Conversion	By using the inverter.	By using a rectifier.
Transformer	Requires for transmission.	Not requires.
Phase and Neutral	Have	Don't Have
Advantages	Easy to measure.	Easily amplify