The property of magnet to attract or repel other substance is known as Magnetism. We know that, there exist an imaginary magnetic field lines around a magnet which is the main source, responsible for the behaviour of the magnets. When these magnetic field lines penetrates through an area perpendicularly, then (The average of the magnetic field lines) X (the area through which it penetrates) is known as Magnetic Flux. Gauss law in magnetism states that the magnetic flux through any closed surface is zero.
In physics, electrostatics deals with the study of electric charges that are stationary i.e. they are slow moving or have very less acceleration. With respect to the static charges
Coulomb stated that “The magnitude of electrostatic force of interaction between two point charges is directly proportional to the scalar multiplication of the magnitude of charges and inversely proportional to the square of the distance between them”. This law is known as Coulomb’s Law.
A charge particle is always surrounded by a field in which other charge particles can experience its force. In other words, the region where a charge particle can exert force on other charge particle is known as Electric Field. It is a vector quantity which means that it has both magnitude as well as direction. For a positive charge the line of force is directed outwards while for a negative charge the lines of force is directed inwards.
Lines of Force Due to and Isolated -ve charge
Lines of Force Due to and Isolated +e charge
Gauss’s Law in Electrostatics
Theorem: Gauss’s Law states that “The net electric flux through any closed surface is equal to 1/ times the net electric charge within that closed surface (or imaginary Gaussian surface)”.
∫ E.ds = q/ϵ
Explanation: In the fig 1.1 two charges +2Q and -Q is enclosed within a closed surface S, and a third charge +3Q is placed outside the closed surface. The net electric flux through the closed surface S will be given by,
ᶲs = ∑ q/ϵ
that is, = (+2Q + (-Q))/ϵ
Since the charge +3Q is placed outside the closed surface, therefore this charge will not be taken into consideration while applying gauss theorem
(Here the imaginary closed Gaussian surface is considered to be a circle
Three types of Application of Gauss’s Law
Magnetostatics is the study of magnetic fields where the current is not changing with time that is, it is steady. The magnetic field produced by a steady current is given by
This is known as Biot- Savarts Law.
Biot-savart law states that:
The magnetic field due to current carrying conductor is directly proportional to a) the magnitude of current b) length of element dL c) sine of angle between r and dL and inversely proportional to the square of the distance between source and the field point. Therefore the total magnetic field due to current carrying conductor is
Gauss law in magnetism states that the magnetic flux through a closed surface is zero. The integral form of gauss law is given by
Where S is any closed surface.
While the gauss theorem strictly deals with the electric field lines, Amperes law deals with the magnetic field lines. Ampere’s law states that the line integral of magnetic field along a closed hypothetical loop (an amperian loop) is equal to μ times the current enclosed by loop where μ is the permeability of the free space.
Both ampere’s law and Biot-Savart’s law help us to calculate the magnitude of magnetic field lines but the basic difference between the biot-savart law and amperes law is that in ampere’s law a symmetric amperian loop is considered along a straight line charge. In other words amperes law is used for symmetrical distribution of currents, while Biotsavart’s law is used for both symmetrical and asymmetrical distribution of currents.
Q.1. What is electromagnetism in physics?
Ans. In physics, electromagnetism is defined as the production of magnetic field lines by the motion of electrons in a current carrying conductor. For Example: solenoid
Q2. What is gauss law of Magnetism?
Ans. Gauss law of magnetism states that the net magnetic flux through any closed surface is zero. The integral form of gauss law is given by
Where S is any closed surface.
Q.3. Do magnetic lines always form closed loops?
Ans. Yes, Magnetic lines always form closed loops. Field line always start from the north pole and ends in the south pole. The magnetic field lines are stronger near the poles.
Q.4. What is gauss law?
Ans. Gauss’s law states that “The net electric flux through any closed surface is equal to 1/ times the net electric charge within that closed surface (or imaginary Gaussian surface)”.
∫E.ds = q/ϵ