Strength of Magnetic Field
The strength of a magnetic field, also known as magnetic field intensity or
H
, measures the contribution of an external current to the magnetic field. It is represented as a vector quantity and is measured in amperes per meter (A/m). The relationship between magnetic field intensity (
H
) and magnetic flux density (
B
) is given by the equation:
where:
-
B
is the magnetic flux density,
-
μ
is the magnetic permeability of the medium,
-
M
is the magnetization of the material.
This equation helps in understanding how the internal magnetization of a material and its permeability affect the overall magnetic field strength.
Biot-Savart's Law
Biot-Savart's Law describes the relationship between electric currents and the magnetic fields they generate. It provides a method to calculate the magnetic field produced by a current-carrying conductor.
According to this law, the magnetic field (
B
) at a point in space due to a small segment of current (
I d
l
) is determined by the vector product of the current segment and the unit vector pointing from the segment to the point of observation.
What Is Lorentz Force?
The Lorentz force is the total force experienced by a charged particle moving through electric and magnetic fields. It combines the effects of both fields on the charge. The Lorentz force (
F
) is given by the equation:
F= q(v * B + E) (This acts normal to v and the work done by it is zero)
where:
-
q
is the charge of the particle,
-
v
is the velocity of the particle,
-
B
is the magnetic field,
-
E
is the electric field,
-
×
denotes the cross product between velocity and magnetic field.
Cyclotron Frequency
Cyclotron frequency refers to the frequency at which a charged particle orbits in a magnetic field. When a charged particle moves in a plane perpendicular to a uniform magnetic field, it experiences a centripetal force due to the magnetic field, which causes it to move in a circular path. The frequency of this circular motion is called the cyclotron frequency.
Ampere’s Circuital Law
Ampere’s Circuital Law relates the magnetic field around a closed loop to the electric current passing through the loop. The law states that the integral of the magnetic field (
B
) around a closed path (
C
) is directly proportional to the total current (
I
) passing through the surface (
S
) bounded by that path. Mathematically, the law is expressed as:
Benefits of CBSE Class 12 Physics Notes Chapter 4 Moving Charges and Magnetism
-
Comprehensive Understanding
: The notes provide a thorough explanation of fundamental concepts such as the force on a moving charge, magnetic field strength, and the Biot-Savart Law. This comprehensive coverage helps students build a solid foundation in electromagnetism.
-
Clear Explanations
: Concepts like Lorentz force, cyclotron frequency, and Ampere’s Circuital Law are broken down into simple, easy-to-understand explanations. This clarity helps students grasp complex topics more effectively.
-
Illustrative Examples
: The notes include various examples and applications, such as calculating magnetic fields and understanding the motion of charged particles. These examples help students see practical applications of theoretical concepts.
-
Mathematical Formulas
: The notes provide important formulas and equations, such as the Lorentz force equation and the formula for magnetic field strength. This inclusion is crucial for solving problems and performing calculations in exams.