Electric charge is a physical property of matter that causes it to experience a force when placed in an electromagnetic field.
An electromagnetic field is a region of space in which an electric charge experiences a force.
Electric potential is defined as the amount of work/energy needed per unit of electric charge to move the charge from a reference point to a specific point in an electromagnetic field.
Voltage is the difference in electric potential between two points.
Electromagnetic interference and noise
Electromagnetic radiation is always present in a production enviroment. It could be mobile networks, solar flares, stroms lightning, ignition systems, etc.
The interaction of electromagnetic radiation with an electrical conductor (such as copper wire) can cause voltage spikes in the conductor. This is called electromagnetic interference.
The noise in an audio signal is the undesired voltage variations in the audio signal that causes artifacts and a loss of signal quality.
Wave phase difference
A wave can be characterized by several key parameters that describe its properties: wavelength, amplitude, frequency, period, velocity and phase.
The following waves share exactly the same value for all those parameters except for the phase value. As can be seen in the figure below, for any given point on the X-axis, the waves have different values on the Y-axis.
On the other hand, the wave graphs can be represented as the graph resulting from the rotation of the radius of a circle. So that any point on the wave can be described by the height at which the radius is located and by the angle at which the radius is located.
Thus as shown below, at a given point on a wave, the Y value of that point on the wave will depend on the height of the radius and the X value of that point on the wave will depend on the angle of the radius.
To measure the angle of the radius in the circle, any point on the circle can be taken as the origin. But that starting point must be the same for all subsequent measurements.
To measure the height of the radius, is the vertical distance between the center of circle and the point of the radius in the perimeter (The red dotted line in the figure)
