What is a Magnetic circuit?
In a magnetic circuit, the magnetomotive force (MMF) is the driving force that causes the magnetic flux to flow. The MMF is defined as the product of the current flowing through the circuit and the number of turns in the circuit. The resistance to the flow of flux in a magnetic circuit is called reluctance. The reluctance of a magnetic circuit depends on the material and geometry of the circuit, as well as the strength of the magnetic field.
In a magnetic circuit, the flux follows a closed path through the circuit, starting from the North Pole of a magnet and ending at the South Pole. The flux can be increased by increasing the MMF or decreasing the reluctance of the circuit. Conversely, the flux can be decreased by decreasing the MMF or increasing the reluctance of the circuit.
What is Electrical Circuit?
An electric circuit is a path through which electric current flows. It is made up of conductive materials such as metal wires or semiconductor devices, and it can also include various electrical components such as resistors, capacitors, inductors, and other devices.
The electric current in an electric circuit is driven by the electromotive force (EMF), which is typically supplied by a voltage source such as a battery or an AC power outlet. The resistance of the circuit, which is determined by the material and geometry of the conductors and other components, opposes the flow of current. The conductance of the circuit, which is the reciprocal of resistance, determines the ease of flow of current.
The behavior of an electric circuit is governed by Ohm's Law, which states that the current flowing through a circuit is directly proportional to the voltage applied and inversely proportional to the resistance of the circuit. Kirchhoff's laws, which include the voltage law (KVL) and the current law (KCL), are also important in the analysis of electric circuits.
Difference Between Magnetic and Electric Circuit
| Property | Magnetic Circuit | Electric Circuit |
|---|---|---|
| Path followed by flux/current | Closed path followed by magnetic flux | Closed path followed by electric current |
| Unit of measure for flux/current | Weber (Wb) | Ampere (A) |
| Driving force | Magnetomotive force (MMF) | Electromotive force (EMF) |
| Opposition to flow of flux/current | Reluctance | Resistance |
| Property that determines ease of flow of flux/current | Permeance | Conductance |
| Property that determines opposition to flow of flux/current | Reluctivity | Resistivity |
| Nature of flux/current | Alignment of molecular poles | Flow of electrons |
| Presence of perfect insulators | No | Yes |
| Constant value of opposition to flow of flux/current | No | Yes (though it can change slightly with temperature) |
| Dissipation of energy | Only required at initial stage to create flux | Continuously dissipated as heat as long as current flows |
| Governing laws | Kirchhoff's flux and MMF law | Kirchhoff's voltage and current law |
| Direction of flow of flux/current | From North Pole to South Pole | From positive charge to negative charge |
- In a magnetic circuit, the closed path followed by the flux is called the magnetic circuit, while in an electric circuit, the closed path followed by the current is called the electric circuit.
- The unit of flux in a magnetic circuit is the Weber, while the unit of current in an electric circuit is the Ampere.
- The driving force in a magnetic circuit is called the magnetomotive force (MMF) and is measured in Ampere-turns (AT), while the driving force in an electric circuit is called the electromotive force (EMF) and is measured in volts (V).
- The opposition to the flow of magnetic flux in a magnetic circuit is called reluctance and is measured in AT/wb, while the opposition to the flow of current in an electric circuit is called resistance and is measured in ohms (Ω).
- In a magnetic circuit, the measure of the ease with which magnetic flux can flow through a material is called permeance and is equal to 1/reluctance, while in an electric circuit, the measure of the ease with which electric current can flow through a material is called conductance and is equal to 1/resistance.
- In a magnetic circuit, the measure of a material's ability to support the flow of magnetic flux is called permeability, while in an electric circuit, the measure of a material's ability to support the flow of electric current is called conductivity.
- In a magnetic circuit, the measure of a material's resistance to the flow of magnetic flux is called reluctivity, while in an electric circuit, the measure of a material's resistance to the flow of electric current is called resistivity.
- In a magnetic circuit, molecular poles are aligned, and the flux does not flow but sets up in the circuit. In an electric circuit, electric current flows in the form of electrons.
- In a magnetic circuit, there is no such thing as a perfect insulator, as flux can set up even in non-magnetic materials like air, rubber, glass, etc. In an electric circuit, there are many materials that can act as perfect insulators, such as glass, air, rubber, PVC, and synthetic resin.
- The reluctance of a magnetic circuit varies with the value of the magnetic field strength (B), while the resistance of an electric circuit is relatively constant and depends on the resistivity of the material.
- In a magnetic circuit, energy is only required to set up the flux at the initial stage, while in an electric circuit, energy is continuously dissipated in the form of heat as long as the current flows.
- The Kirchhoff flux and MMF laws are followed in a magnetic circuit, while the Kirchhoff voltage and current laws (KVL and KCL) are followed in an electric circuit.
- In a magnetic circuit, the lines of flux start from the north pole and end at the south pole, while in an electric circuit, the lines of current start from a positive charge and end at a negative charge.
- The magnetic field in a magnetic circuit is typically generated by a magnet, while the electric field in an electric circuit is generated by a voltage or potential difference.
- Magnetic circuits are often used to transmit power, while electric circuits are used to transmit both power and information.
- Magnetic circuits can be used to control the flow of electric current in devices like transformers, relays, and motors.
- The strength of the magnetic field in a magnetic circuit is determined by the magnetomotive force (MMF) and the reluctance of the circuit, while the strength of the electric field in an electric circuit is determined by the voltage and the resistance of the circuit.
- The flow of flux in a magnetic circuit is governed by Faraday's Law of Electromagnetic Induction, while the flow of current in an electric circuit is governed by Ohm's Law.
- Magnetic circuits are often used in devices like speakers, microphones, and earphones, while electric circuits are used in devices like computers, smartphones, and appliances.
- The properties of magnetic materials (such as permeability and reluctivity) can be affected by the temperature and applied magnetic fields, while the properties of electrical materials (such as conductivity and resistivity) can be affected by temperature and applied electric fields.
- Magnetic circuits can be used to store data in devices like hard drives, while electric circuits are used to process and transmit data in devices like computers and servers.
- Magnetic circuits can be used to generate mechanical forces (such as in motors and generators), while electric circuits are often used to control the movement of mechanical devices (such as in actuators and servomechanisms).