8TH GRADE · MAGNETIC PHENOMENA
Magnetic field action and motor
The Earth's field, the left-hand rule and the principle of the electric motor.
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Basic Concepts
Action of the field on the conductor
A magnetic field exerts a force on a current-carrying conductor if the current is not directed along the field lines.
The direction of the force is determined by the left-hand rule, taking into account the direction of the current and magnetic induction.
Electric motor
A device that converts electrical energy into mechanical energy due to the action of a magnetic field on a current.
Forces on opposite sides of the frame create torque, and switching the direction of the current maintains rotation.
Earth's magnetic field
The Earth creates a magnetic field that orients the compass needle approximately along the magnetic meridian.
The magnetic and geographic poles do not coincide, and the field partially protects the atmosphere from charged particles from the Sun.
Physical quantities
Magnetic induction
Strength characteristics of the magnetic field.
Unit: Tesla ·
Force on conductor
The magnetic field force acting on a current-carrying conductor.
Unit: newton ·
Conductor length in field
The length of a section of conductor located in a magnetic field.
Unit: meter ·
Lesson formulas
Force on a current-carrying conductor
With a perpendicular field, the force is equal to the product of induction, current and active length of the conductor.
Condition: The conductor is perpendicular to the lines of a uniform magnetic field.
Related formulas
The same formulas in the reference, with symbols and units.
Tasks on the topic
Statements, answer options and the walkthrough.