Magnetism Flashcards
Expression for magnetic induction at a a point in the axis at a distance x from the centre of a circular coil of radius a, carrying current i
B= μ0ia*a/(2(a^2 + x^2)^(3/2))
= (μ0/4π)*(2M/(x^3))
Properties of magnets
Directive property
Attractive property
Earth behaves as a magnet with magnetic field pointing approximately from geographical south to geographical north.
Magnetic monopoles do not exist.
Magnetism has its origin in circulating charges within the atoms of any substance.
Expression for magnetic dipole moment
M=IA
Magnetic dipole moment of a revolving electron - Derivation
T= 2πr/v i= e/T M= evr/2
What is the direction of magnetic moment of a rotating electron?
Into the plane of paper
Negative charged electrons move in anti-clockwise direction leading to clockwise current.
Relation between orbital angular momentum and orbital magnetic moment of an electron
__ __
M = -(e/2m)*L
In opposite directions
Define Gyromagnetic ratio
The ratio of magnetic dipole moment with angular momentum of revolving electron is called Gyromagnetic ratio.
Expression for Gyromagnetic ratio
M/L = e/2m
Value of Gyromagnetic ratio
8.8 * 10^8 C/kg
Define magnetization
The net magnetic dipole moment per unit volume of the sample is called as the magnetization of the sample.
Expression for magnetization
___ ___
Mz= Mnet/Volume
What is the unit of magnetization?
A/m
Is magnetization a scalar or vector quantity?
Vector
Dimensions of magnetization
[L-1 M0 T0 I1]
Define saturation of the sample
Complete alignment of the atomic dipole moment is called saturation of the sample.
State Curie law
Curie law states that, magnetization of a paramagnetic sample s directly proportional to the external magnetic field and inversely proportional to the absolute temperature.
What is the equation for Curie law?
Mz= C*Bext /T
What is magnetic intensity?
The vector quantity in terms of which strength of the magnetic field at a point can be given is known as magnetic intensity.
Relation between magnetic field and magnetic intensity
Bo=μο*Η
Unit of H
A/m