Fundamentals of Electrostatics and Electrodynamics
Electrostatics: When the charge is at rest. Electrodynamics: The energy or electric charge in motion. Current Load: The basic and inherent property of matter; there are loads + or -, and the charges repel and attract each other. Unit Basic Load: What is an electron or a proton? Bodies Drivers: Materials whose electrons can move freely through them. Electrification: When charges are attracted to other bodies and divided into: friction, contact, induction. Electric Force: The force depends on the magnitude or intensity, the distance between them, and the amount of charge (F) (IF = N). Coulomb’s Law: The electrical force between two charged bodies can be attractive or repulsive; it is directly proportional to the product of the charges and inversely proportional to the square of the distance between their centers. 1 Coulomb: The amount of charge able to act in a vacuum on another charge with a strength of 9×109 N when separated by a distance of one meter. Electric Field: An area or space in which the presence of an electrical force on another charge placed in that area is noted. Field Strength Electricity: The force exerted by the electric field on each unit charge located at that point (E). Lines of Force: Imaginary lines that represent the characteristics of an electric field, departing from a positive charge and going to a negative charge or inward. Electricity: The orderly movement of electrical charges through a conductor between two points that are subjected to an electrical potential difference. The Current: Corresponds to the amount of charge passing through a conductor’s cross-section in each unit of time. Current: The direction of flow of electrical charges does not change; this is what happens in a battery. Alternating Current: In this case, the direction of flow of electrical charges through the conductor switches alternately; this is used in large quantities in household or industrial networks. Resistance Electricity: The opposition that a conductor has to the passage of electric current through it; electrical resistance is a characteristic of each conductor. The Electrical Resistance Depends On:
- Material: Specific resistance (rho ℮)
- Length (L)
- Cross Section (s)
Electrical resistance of a conductor is affected by temperature variation, as a change in temperature produces changes in its dimensions. Resistance: Resistivity, for comparing the electrical resistance of two conductors. Corresponds to the electrical resistance of a conductor of a material which has unit length and unit area for the cross-section at 0 °C. Ohm’s Law: When a conductor is subjected to different voltages (potential differences), the electrical current also changes. The current and voltage are directly proportional variables; most metals comply with Ohm’s law. Those that do not comply are called non-ohmic materials. Physical Quantities: The various physical quantities are classified under two criteria: according to how they arise and how they are expressed. From the standpoint of how they arise, physical quantities can be fundamental or derived. For the fundamental mechanics, the following are chosen: length, mass, time. The derived quantities are all defined from the essentials: speed, momentum, velocity. Scalar: Those that are defined solely by a number. Vector: Those that are completely defined by a magnitude (size, absolute), direction, and address.
Parameters of a Movement:
- Path: The path of a body in motion.
- Position: The location of a mobile object for a reference.
- Distance: Corresponds to the length of the path.
- Average Speed: Defined as the ratio between the distance and time:
Vm = distance / time
Average Speed: Defined as the ratio of the displacement produced and the time spent:
Vm = average speed
r = displacement
Time
The Path Length: The distance traveled by the mobile object. The displacement is the change in position of a body and does not depend on the shape of the trajectory. The Average Speed: The ratio between the distance traveled and the time interval, and average speed is the ratio of displacement of a mobile object and the time interval. The Speed: That a body carries depends on the frame from which its movement is observed. A single mobile object can have different speeds depending on the frame. According to the movement path, it can be straight, circular, elliptical, or parabolic. Given the Speed: The movement can be: uniform motion, rectilinear uniform motion, or varied uniformly varied motion. MU: Occurs when the speed is constant, meaning that the mobile travels equal distances in equal time intervals. MUR: Constant rate.
Cross Section = s = “pi” r2
D