11TH GRADE · MAGNETISM
Magnetic field and forces
Induction, Ampere force, Lorentz force and charge motion.
The entire theory of the lesson is collected here; you can read it without an account. In interactive mode, the same theory appears as cards, followed by questions. with checking the answer and task, and progress is saved.
Basic Concepts
Magnetic field
A field created by moving charges and acting on moving charges and currents.
The magnetic part of the force is perpendicular to the speed of the charge, therefore it changes the direction of movement, but does not do work.
Ampere power
The force of a magnetic field on a conductor carrying an electric current.
The force is maximum when the conductor is perpendicular to the field and is zero when the current is directed along the magnetic induction.
Lorentz force
The force of electric and magnetic fields on a moving charge.
The electrical part of the force can change the speed modulo, while the magnetic part is directed across the movement and bends the trajectory.
Physical quantities
Magnetic induction
Strength characteristics of the magnetic field.
Unit: Tesla ·
Ampere power
The magnetic field force acting on a current-carrying conductor.
Unit: newton ·
Active conductor length
The length of a section of conductor located in a magnetic field.
Unit: meter ·
Angle to magnetic field
The angle between the direction of current or speed and the vector of magnetic induction.
Unit: radian ·
Magnetic Lorentz force
The force of a magnetic field acting on a moving charge.
Unit: newton ·
Charge speed
The speed of movement of a charged particle.
Unit: meter per second ·
Particle charge
Electric charge of a moving particle.
Unit: pendant ·
Particle mass
Inert mass of a moving particle.
Unit: kilogram ·
Trajectory radius
The radius of the circle along which the charge moves.
Unit: meter ·
Maximum torque
The greatest torque acting on the current-carrying frame.
Unit: newton meter ·
Frame area
Area of the current loop.
Unit: square meter ·
Lesson formulas
Determination of magnetic induction
Magnetic induction can be determined by the force on the conductor or the maximum moment on the frame.
Definition of Tesla
One tesla creates a force of one newton on a one meter long conductor with a current of one ampere.
Ampere power
The Ampere's strength depends on the current, the length of the conductor, the induction and the angle.
Magnetic Lorentz force
The magnetic force on a charge depends on the charge, speed, induction and angle.
Charge movement in a circle
Magnetic force plays the role of centripetal force.
Condition: The speed is perpendicular to the magnetic induction.
Charge trajectory radius
The radius increases with mass and speed, decreases with charge and induction.
Charge reversal period
The period of revolution in a uniform field does not depend on the speed.
Related formulas
The same formulas in the reference, with symbols and units.
Tasks on the topic
Statements, answer options and the walkthrough.