What is Electric Сurrent [Audio Physics for Beginners]

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In the previous article we are considered what is voltage. Voltage, electrical current and resistance are the main basics of the electricity. Today we consider the current in context of audio as physics part.

What is Electric current

By the existing theory, electrical current is moving of electrons.

Voltage cause the moving from point with higher potential to point with lower potential.

Electrons move across wires like a pipe.

Let’s imagine cross-section (ring) inside the pipe as shown in the picture.

What is amperage of the electric current

What is amperage of the electric current

The ring is infinite thin.

Amperage is the number of the electrons that pass thru the ring per second.

The number of the electrons called as electrical charge.

The amperage is called as I.

Above we considered direct current. The current in single direction.

Voltage in point may be changed. Let's imagine 2 points A and B.

In current moment point A have higher electrical potential than point B.

Electrons moves from point with higher potential A to point with lower potential B.

In next time moment point B have higher potential than point A.

Electrons moves in the opposite direction from point with higher potential B to point with lower potential A.

It is alternating current.

Alternating current

Alternating current

Let's pay attention to potentials. There is one subtle detail.

At the battery we can see 2 contacts "+" and "-". At the battery's body we can read 1.5 V.

It is mean, that voltage (difference of electrical contact potentials) between "+" and "-" is 1.5 Volt.

Voltage (potential difference)
of electrical battery

Voltage electrical battery

Mathematically potential "+" (positive potential) more that "-" (negative). And electrons should move from higher potential to lower one: from "+" to "-".

However, electrons is negative charged particles. So in reality they moves for "-" to "+". It is reason why negative contact should be disconnected when an electrical device is turned off.

But when we learn electrical schemes, we consider "virtual" positive particles, that moves from "+" to "-".

Therefore, us need follow context when we discuss the electric current direction.

In the next article we will look in details how voltage and current are bound.

< Electric voltage Electrical Resistance >

Yuri Korzunov,

Audiophile Inventory's developer

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