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CBSE Class 12 » CBSE Class 12 Study Materials » Physics » Ampere’s Law
CBSE

Ampere’s Law

In this article, we will learn about ampere's law, ampere's law formula, ampere's law meaning, applications of ampere's law, ampere’s circuital law and more. We will also discuss some important questions as well.

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One of the most important laws of electromagnetism is Ampere’s Law. Determining the expression for any closed-loop path is what this is all about. It states that the permeability times the electric current is equal to the sum of length elements times the magnetic field in the direction of length element. This law helps us to keep a proper bridge between electricity and magnetism in place. It also shows how magnetic fields and electric currents are related mathematically. The magnetic field created by an electric current flowing through a wire of any shape can be calculated using Amperes’ law.

Ampere’s Law

Ampere’s law is a useful law that connects the net magnetic field along a closed loop to the electric current that flows through it. Andre-Marie Ampere found it in the year 1826. The Ampere’s law is an expression describing the relationship between the magnetic field and the current that produces it.

The line integral of the magnetic field around any arbitrary path is proportional to the net electric current enclosed by that channel. This is the statement of Ampere’s law. Furthermore, Maxwell generalised this law to include magnetic fields that emerge from sources other than current. As a result, one of the four Maxwell equations is Ampere-law. Maxwell’s.

André-Marie Ampère was a scientist who studied the forces occurring on current-carrying wires. The experiment happened in the 1820s, when Faraday was working on Faraday’s Law. Faraday and Ampere’s law had no idea that four years later, Maxwell would include their work.

Ampere’s Law: Formula

The ampere’s law is given as

∅B ds=μ0I

And also

∇×H=∂D/∂t+J

This is the final equation of maxwell.

Here,

μ0 = permeability of free space

I = current

J = current density

∇= divergence

Ampere’s Law: Concept

Ampere’s Law requires that all currents be constant. As a result, the current does not alter across time. Also, only currents crossing the path’s interior must be included, as they will contribute to the magnetic field in some way. Currents must be interpreted in terms of their algebraic signs. To evaluate its directions and signals, one can apply the right hand’s rule. When the magnetic field is normal to the given path at any point, the total magnetic circulation will be zero. When computing the magnetic fields of current distributions with a high degree of symmetry, Ampere’s Law will come in useful.

Ampere’s Circuital Law

The magnetic field owing to dispersed currents is calculated using Ampere’s Circuital Law. It’s similar to the Gauss law, which estimates the electric field owing to distributed charges in electrostatics. The magnetic field owing to a given current distribution can be calculated using Ampere’s Circuital Law.

According to the Ampere’s Circuital Law, Line integral of magnetic field B around closed curve is equal to 0 times the total current I flowing through the curve’s enclosed area.

Therefore, the Ampere’s Circuital Law is given as

B ds=0I

Maxwell’s Law

Maxwell simplified the complete theory of electromagnetic in four equations after discovering Ampere’s law which is considered as Maxwell’s laws.

One of these is Ampere’s law, which has been extended to include a time-dependent dielectric shift. However, Maxwell’s laws are frequently expressed in differential form, that is, equations which give relationships between the derivatives of electric and magnetic fields, rather than integrals as before.

According to Maxwell’s law

×H=∂D∂t+J

Applications of Ampere’s Circuital Law

There are many applications of Ampere’s Circuital Law, some of which are as follows.

  1. Ampere’s Circuital Law is used to determine the magnetic induction which occurs when a long current-carrying wire is used.
  2. Ampere’s Circuital Law is used to determine the magnetic field inside a toroid.
  3. Ampere’s Circuital Law used to calculate the magnetic field which is produced by a long current-carrying conducting cylinder.
  4. Ampere’s Circuital Law is used when the magnetic field inside the conductor must be determined.

Conclusion

The line integral of the magnetic field around any arbitrary path is proportional to the net electric current enclosed by that channel. This is considered as Ampere’s law. 

The ampere’s law is given as

B ds=0I

According to the Ampere’s Circuital Law, Line integral of magnetic field B around closed curve is equal to 0 times the total current I flowing through the curve’s enclosed area.

B ds=0I

According to Maxwell’s law

×H=∂D∂t+J

Ampere’s Circuital Law is used to determine the magnetic induction which occurs when a long current – carrying wire is applied.

Ampere’s Circuital Law is used to determine the magnetic field inside a toroid.

faq

Frequently asked questions

Get answers to the most common queries related to the CBSE Class 12 Examination Preparation.

What is Ampere's law?

Answer: According to Ampere’s rule (or law), the magnetic field produced by an electric current is proportiona...Read full

What is Ampere's Circuital Law?

Answer: The line integral of magnetic field surrounding a closed-loop equals the algebraic total of currents going t...Read full

When do we apply the Ampere’s circuital law?

Answer: In introductory Electromagnetic theory, you can use Ampere circuital law when the symmetry of the situation ...Read full

What are the applications of ampere's law?

Answer: Ampere’s law has a wide range of applications. Its primary use is to calculate the magnetic field prod...Read full

Answer: According to Ampere’s rule (or law), the magnetic field produced by an electric current is proportional to its size, with a proportionality constant equal to the permeability of free space.

The main issue with Ampere’s Law is that Ampere’s Law is a differential equation, which means that it requires some mathematics to apply.

The ampere’s law is given as

∅B ds=μ0I

Answer: The line integral of magnetic field surrounding a closed-loop equals the algebraic total of currents going through the loop.

Ampere’s Circuital Law is as follows

∅B ds=μ0∑I

Answer: In introductory Electromagnetic theory, you can use Ampere circuital law when the symmetry of the situation allows it, that is if the magnetic field surrounding ‘Amperian loop is constant. Calculating the magnetic field of an infinite straight current carrying wire at a specified radial distance is the example for this.

Answer: Ampere’s law has a wide range of applications. Its primary use is to calculate the magnetic field produced by an electric current. Electromagnets, motors, generators, transformers, and other devices can benefit from this. Ampere’s law simplifies many calculations by employing a specific symmetry.

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