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Electromagnetic damping is a technique used to control the motion of an object. It helps to reduce the moving speed of a thing. Linear, oscillatory, and rotatory are various types of movement by an object. Hence, several damping techniques are used in a system such as air, conventional fluid, and electromagnetic friction damping.
| Table of Content |
Key Terms: Damping, Current, Force, Induction, Flux, Lenz Law, Motion, Air, Conventional fluid, Electromagnetic friction damping, Damping force, Conductor, Magnet
Electromagnetic Damping
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One of the remarkable strategies. It induces the current electromagnetically to regulate object motion without any physical contact. Moreover, it is essential to know about induction and Eddy's current for understanding this process. Damping force increases according to the decrease distance between conductor and magnet. So, the damping rises stand on the speed of an object.
Electromagnetic Damping
Check Important Notes for AC Generator
Electromagnetic Induction
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Michel Faraday was the first one to depict the concept in 1831. Due to the change of magnetic flux, the formation of electric current(e.m.f) in a closed coil is electromagnetic induction. It accomplishes this by surrounding a conductor with a magnetic field. The proportionality constant is inductance. It determines by material qualities.
Electromagnetic Induction
Features of Inductance
- Scalar quantity
- Dimension: M L2 T–2 A–2
- SI unit of inductance: henry(H)
- Self Inductance: The change of current opposes the electromotive force is self-induction. Consider L as the self-inductance of a coil, N as several turns, Current denote as I, and Φ is magnetic flux. So, the equation is,
L = N Φ /I - Mutual Induction: Place two coils close together. The coils are primary(P-coil) and secondary(S-coil). A battery and key connect to the primary coil and galvanometer to S-coil. An opposing electromotive force produces in each coil due to a change in magnetic flux. This phenomenon is mutual induction. The basic formula is,
M = μ0 μr N1 N2 A / l
(Free space permeability – μ0, Soft iron core permeability - μr, Number of turns – N, Cross-sectional area – A and Length of coil – I)
Also Read:
| Related Concepts to Inductance | ||
|---|---|---|
| Faraday’s Law of Induction | Unit of Magnetic Flux | Faraday Constant |
| Inductance Formula | Magnetic Induction Formula | Faraday's Law of Electromagnetic Induction |
Faraday Law
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Several contributions to science did by Faraday. The invention of an electric generator, motor, and transformer credits by him. One of the notable scientists in the 19th century.
On the experiment basis, Faraday provides three laws,
- Cause of induced e.m.f: An e.m.f produces in a coil when magnetic flux links with changes in the circuit or a closed coil.
- Duration of induced electric current: The current lasts due to a change in continuous magnetic flux.
- Magnitude of e.m.f: Magnitude of current in a coil proportional to magnetic flux change rate.
The mathematical form of theory: ε = -N d ΦB/dt
Also Check: Electromagnetism
Eddy Current
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Current flowing causes a charge to generate across the conductor. Induced electricity is known as eddy current. The electrons form by a unique pattern that swirls around a conductor. Furthermore, a magnetic field generates with the swirl conductor. Foucault is the one who discovers it. The eddy current forms various applicable energy. For example, the slight drift of metal plates in the air is due to this current. The electric power meter is another example.
Eddy Current
Also Read:
| Related Articles | ||
|---|---|---|
| Energy Consideration | Eddy Currents | Inductance |
| AC Generator | Electromagnetism | Solenoid Engine |
| Faraday Constant | Electromagnetic Induction | Motional emf |
Formulas and Law relate to Electromagnetic Damping
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Electric charges create a magnetic field. Several experiments assist the formation of findings. Hence, equations are generating to know the result rather than assumptions. Given below are some of the formulas link with electromagnetic damping.
The passage of entire magnetic lines through a surface area is magnetic flux (Φ B). It lies in vector quantity. The SI unit is Tesla meter square or Weber. Magnetic flux through a magnetic field B and plane area A written as,
Φ B = B. A= BA Cos θ
In 1834, German scientist Friedrich Lenz formulated the principle. It states that current produce by induced e.m.f opposes magnetic flux change. Moreover, it helps to find the direction of the induced current.
- The magnitude of induced e.m.f according to Faraday Law,
ε = Blv
Also Check: Electromagnetic Induction
Things to Remember
- Damping force increase due to less distance between magnet and conductor.
- Eddy current is the process to understand electromagnetic damping.
- Michel Faraday is best known for creating the term electromagnetic induction.
- Lenz law state that current produce by induced e.m.f opposes a change in magnetic flux.
Also Check: Class 12 Physics Chapter 6 Electromagnetic Induction
Previous Year Questions
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Sample Questions
Ques: Describe the self-inductance of a coil and depict the unit? (2 Mark)
Ans: The change of current opposes the electromotive force is self-induction. Although, the unit of inductance is henry(H). Consider L as the self-inductance of a coil, N as several turns, Current denote as I, and Φ is magnetic flux. So, the equation is,
L = N Φ /I
Ques: Define Lenz’s Law? (2 Mark)
Ans: In 1834, German scientist Friedrich Lenz formulated the principle. It states that current produce by induced e.m.f opposes magnetic flux change. Moreover, it helps to find the direction of the induced current.
Ques: How does Faraday law contribute to induction? (3 Mark)
Ans: On the experiment basis, Faraday provides three laws,
- Cause of induced e.m.f: An e.m.f produces in a coil when magnetic flux links with changes in the circuit or a closed coil.
- Duration of induced electric current: The current lasts due to a change in continuous magnetic flux.
- Magnitude of e.m.f: Magnitude of current in a coil proportional to magnetic flux change rate.
The mathematical form of theory: ε = -N d ΦB/dt
Ques: The metallic and glass bob of the same size falls from the same height. Which one reaches the ground earlier and depicts the reason? (2 Mark)
Ans: Due to eddy current, there is a force acting upward. It led to the slow metallic bob. So, the glass bob reaches fast to the ground.
Ques: Write any two examples of eddy current? (2 Mark)
Ans: The eddy current forms various applicable energy. For example, the slight drift of metal plates in the air is due to this current. The electric power meter is another example.
Ques: Explain the mutual inductance of a coil. (3 Mark)
Ans: Place two coils close together. The coils are primary(P-coil) and secondary(S-coil). A battery and key connect to the primary coil and galvanometer to S-coil. An opposing electromotive force produces in each coil due to a change in magnetic flux. This phenomenon is mutual induction. The basic formula is,
M = μ0 μr N1 N2 A / l
Ques: What is magnetic flux? (2 Mark)
Ans: The passage of entire magnetic lines through a surface area is magnetic flux (Φ B). It lies in vector quantity. The SI unit is Tesla meter square or Weber. Magnetic flux through a magnetic field B and plane area A written as,
Φ B = B. A= BA Cos θ
Ques: Define inductance and its unit. (2 Mark)
Ans: The proportionality constant is inductance. It is measure by the quality of the materials. Henry is the SI unit (H). Self and mutual inductance are the two kinds of inductors.
Ques: Does a thin wire act as an inductor? (1 Mark)
Ans: A thin wire does not act as an inductor. A tiny wire cannot contain a considerable magnetic flux. So, it never behaves as an inductor.
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