Work current- this is the work of an electric field to transfer electric charges along a conductor;

The work of the current in the section of the circuit is equal to the product of the current strength, voltage and time during which the work was performed.

Applying the Ohm's law formula for a section of a circuit, you can write several formula options for calculating the work of the current:

According to the law of conservation of energy:

work is equal to the change in the energy of a section of the circuit, therefore, the energy released by the conductor is equal to the work of the current.

In the SI system:

JOLE'S LAW OF LENCH

When current passes through the conductor, the conductor heats up, and heat exchange with the environment occurs, i.e. the conductor gives off warmth to the bodies around him

The amount of heat released by a conductor with a current into the environment is equal to the product of the square of the current strength, the resistance of the conductor and the time the current passes through the conductor.

According to the law of conservation of energy, the amount of heat released by a conductor is numerically equal to the work that the current flowing through the conductor does during the same time.

In the SI system:

[Q] \u003d 1 J

DC POWER

The ratio of the work of the current during the time t to this time interval.

In the SI system:

Electrostatics and DC Laws - Classy Physics

Curious

Footprints in the sand

If you've ever walked on the beach at low tide, then you've probably noticed that as soon as your foot steps onto wet, hard sand, it immediately dries up and turns white around your footprint. This is usually explained by the fact that under the weight of the body, water is "squeezed" out of the sand. However, this is not the case, because the sand does not behave like a washcloth. Why does the sand turn white? Will the sand stay white all the time you are standing still?

It turns out ...
The whitening of sand on a beach was first explained by Reynold in 1885. He showed that the volume of sand increases when stepped on. Before that, grains of sand were "packed" in the most dense way. Under the influence of shear deformation, which occurs under the sole of the shoe, the volume occupied by the grains of sand can only increase. While the sand level rises sharply, the water level can only rise as a result of capillary phenomena, and this takes time. Therefore, at the bottom of the footprint, the sand for some time is above the water level - it is dry and white.

Physics

DC operation and power

Energy transformation mechanism in a conductor with current... By forcing free carriers to move in a conductor, the applied electric field does work. According to the law of conservation of energy, the work done on a section of the circuit should be equal to the change in the energy of this section. Let the current in the conductor be constant in time and is due to the ordered movement of electrons. Electric field accelerates electrons, while doing work due to an external source. As a result of collisions of electrons with ions of the crystal lattice, the latter transfers part of the kinetic energy of electrons, which leads to an increase in the energy of ion vibrations, i.e. to increase the internal energy of the conductor. This means that the temperature of the conductor increases, it heats up and begins to transfer energy to the environment. After a short time, thermal equilibrium is established, i.e. The energy continuously supplied to the conductor due to the work of an external source is transferred to surrounding bodies in the form of a quantity of heat. The conductor itself does not heat up anymore.

DC work and power. Let the circuit section be energized U... During D t charge passes through the cross-section of the conductor D q \u003d ID t... The electric field does the work A \u003d D qU.

Hence: the work of electric current

The formulas are equivalent:

Power current

(10.2)

The power released across resistors in a complex DC circuit depends on how these resistors are connected. When connected in series, the current through the resistors is the same and the power is proportional to the resistance. When connected in parallel, the voltage is the same and the power is inversely proportional to the resistance.

Joule-Lenz law. The amount of heat released by a conductor with current into the environment is determined by the formula