Electromagnetic Damping

The induced eddy current, magnetic field strength, and object speed all contribute to the electromagnetic damping force. Which means that as the object moves faster, the damping will increase, and as the object moves slower, the damping will decrease, resulting in a smooth halt.

Other types of dampening exist. Electric resistance dampens resonant electric circuits in which another current surges back and forth, such as in a radio or television receiver. To sustain resonance, the signal to which the receiver is tuned supplies energy synchronously.

Radiation damping converts the vibrational energy of moving charges, such as electrons, to electromagnetic energy, which is then emitted as radio waves, infrared light, or visible light.

Electromagnetic Damping

Electromagnetic damping is one of the most exciting damping techniques among all the damping techniques. Electromagnetic damping uses electromagnetically induced current to control/regulate/slow down the motion of an object without any actual physical touch with the moving object. To comprehend this intriguing dampening approach, it is necessary to grasp two concepts: Eddy current and Electromagnetic induction.

Damping

In physics, damping is the process of dissipating energy to prevent vibratory motions such as mechanical oscillations, noise, and switching electric currents. Because of dampening, a swing’s motion diminishes down unless a youngster continually pumping it. Automobile shock absorbers and carpet pads are two examples of dampening devices.

It’s possible that a system is so dampened that it can’t vibrate. Critical damping simply prevents vibration or allows the item to return to its state of rest in the quickest possible time. A critically damped device is a car shock absorber, for example. Extra damping causes the device to be overdamped, which in some cases, such as in door closers, is advantageous. An underdamped system’s vibrations gradually decrease to zero.

                                               Damped waves

Mechanical dampening comes in a variety of forms. Friction, also known as dry or Coulomb damping in this context, results primarily from electrostatic forces of attraction between sliding surfaces and metal gate energy of motion, or change in momentum, into heat.

Electromagnetic induction

The concept of electromagnetic induction was initially researched by Michel Faraday in 1831. “Changing magnetic field and induced emf (electromotive force) into a conductor,” he defined electromagnetic induction. It is accomplished by moving a conductor over a constant magnetic field or by placing the conductor in a fluctuating magnetic field.

Eddy current

The induced emf that causes a current to flow across a conductor is known as the Eddy current. The electrons in the conductor follow a distinct pattern, swirling around the conducting line like water in a whirlpool due to Eddy current.

The eddy current in the conductor swirls in this fashion to form a magnetic field in the system. The conductor is also exposed to an external magnetic field. According to Lenz’s law, the magnetic field generated by eddy current opposes the change in the magnetic field experienced by the conductor. As a result, Eddy current swirls perpendicular to the magnetic field.

Electromagnetic damping Examples

Let’s look at an example to help you comprehend eddy currents:

Let’s say there’s a source of B vector B. The Law of Faraday in the conductive plate will be triggered by a change in magnetic flux if we shift a metallic plate towards and apart from the source of B axis B emf.

∈=-d∅/dt

∈=-d∅dt

Application

Magnetic damping is used in sensitive laboratory balances, for example. The balance must be as friction-free as feasible in order to have optimal sensitivity and accuracy. However, if there is no friction, it will oscillate for a very long time. Magnetic damping is a straightforward and effective solution. Drag is proportional to speed with magnetic dampening and becomes zero at zero speed. As a result, the oscillations are swiftly dampened, and the damping force then vanishes, allowing the balance to be extremely sensitive. Magnetic damping is achieved in most balances by rotating a conducting disc in a fixed field.

Recycling facilities can employ magnets to separate metals from other materials since eddy currents and magnetic damping only occur in conductors. Trash is deposited in batches down a ramp, which is surrounded by a powerful magnet. Magnetic damping slows conductors in the rubbish, while nonmetals in the trash go on, separating from the metals. This applies to all metals, not just those that are ferromagnetic. By working on stationary garbage, a magnet may separate ferromagnetic materials.

The theory behind electromagnetic damping

A damping force is created when the Eddy current and magnetic field interact with each other. Electromagnetic damping is the term used to describe the preceding sentence. It opposes the conductor’s/movement. object’s Electromagnetic damping is a damping technique in which an electromagnetically produced current slows the motion of an object again with no real touch.

The dependency of electromagnetic damping

As the distance between the magnet and the conductor shrinks, the damping force increases. The electromagnetic damping force is directly proportional to the induced eddy current, magnetic field strength, and object speed. Which means that if the object goes quicker, the damping will be higher, and if the object moves slower, the damping will be lower, resulting in a smooth stop.

Conclusion

The movement of a magnetic field across a conductor creates an eddy current in the conductor. The passage of electrons in the conductor immediately creates an opposite magnetic field, causing the magnet to dampen and heat to build up inside the conductor, similar to how heat builds up inside a power cord during operation. The change in kinetic energy lost by the magnet is equal to the amount of heat transferred to the conductor in the form of heat – the greater the loss of thermal energy of a magnet (a product of its mass and velocity), the greater the heat build up in the conductor and more forceful the damp effect.