10TH GRADE · ELECTROSTATICS
Charge and electric field
Law of conservation of charge, Coulomb's law, tension and superposition.
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
Law of conservation of electric charge
The algebraic sum of the charges of an electrically isolated system remains constant.
Charge can transfer between bodies and be redistributed, but this does not change the total charge of an isolated system.
Coulomb's law
The law of interaction of stationary point electric charges.
The force is directed along the line between the charges, depends on their signs and decreases in inverse proportion to the square of the distance.
Electric field
A form of matter through which electric charges interact with each other.
The field exists around the charge and at each point it determines what force would act on a unit positive test charge.
Principle of field superposition
The field of several sources is equal to the vector sum of the fields of each source.
The contribution of each source is calculated separately, and then the tension vectors are added up, taking into account their directions.
Physical quantities
Electric charge
A quantity that determines the electrical interaction of a body.
Unit: pendant ·
First electric charge
Charge of the first interacting body.
Unit: pendant ·
Second electric charge
Charge of the second interacting body.
Unit: pendant ·
Coulomb constant
Electrical interaction coefficient in vacuum.
Unit: newton square meter per square pendant ·
Relative dielectric constant
How many times is the field in the medium weaker than the field in vacuum with equal free charges?
Unit: dimensionless quantity
Electrical constant
Fundamental constant characterizing the electric field in a vacuum.
Unit: farad per meter ·
Electric field strength
Force acting on a unit positive test charge.
Unit: newton per coulomb ·
Field strength in vacuum
Electric field strength in the absence of a dielectric medium.
Unit: newton per coulomb ·
Lesson formulas
Law of conservation of charge
The algebraic sum of charges of an isolated system is constant.
Coulomb's law
The strength of charge interaction depends on the charges, distance and properties of the medium.
Definition of tension
Tension is equal to the force per unit positive test charge.
Tension units
A newton per coulomb is equal to a volt per meter.
Point charge field
The intensity of a point charge decreases in inverse proportion to the square of the distance.
Dielectric constant across fields
Dielectric constant shows the field weakening in the medium.
Superposition of tensions
The intensity of several sources is equal to the vector sum of the individual intensities.
Coulomb constant
The Coulomb constant specifies the strength of electrical interaction in a vacuum.
Electrical constant
The electric constant characterizes the electric field in a vacuum.
Related formulas
The same formulas in the reference, with symbols and units.
Tasks on the topic
Statements, answer options and the walkthrough.